user-1: Genjokoan says

Birth is an expression complete this moment. Death is an expression
complete this moment. They are like winter and spring. You do not call
winter the beginning of spring, nor summer the end of spring.

Dogen says here that spring is not after winter, but there is still "before" and "after", which is included in spring, and spring is independent of them. etc.

If not the beginning of spring, what is before spring? Not winter.

And if - likewise - the end of life is discontinuous with the present, does that mean life does not end when I only exist in the present?

user19480: Dogen is said to have said:

Time itself is being, and all being is time.
But what does “is” mean, and how does it help form the answer being searched for by the OP?

In the question, the OP interprets what Dogen said, in the text that the OP quoted, as meaning:

Dogen says here that spring is not after winter, but there is still "before" and "after", which is included in spring, and spring is independent of them. etc.

But Dogen said:

Birth is an expression complete this moment. Death is an expression complete this moment. They are like winter and spring. You do not call winter the beginning of spring, nor summer the end of spring.

Lets deal with the first two assertions, and leave the metaphor for a moment. In the quote from Dogen’s “Uji,” there is the line:

Time is not separate from you, and as you are present, time does not go away.

We are so used to being told what to think, we have forgotten what it means to be. I like to ask of others, “Today, we know that the heart pumps blood, but before humans invented the water pump, what was the heart for?”
Of course, if we give it some time, and don’t just shut the question out of our thoughts, we all know what the heart is for—and it’s not to be a pump. Why? Because before we were told what it was, we all could experience it ourselves—and we still do. It’s just that when we are confronted today with a question, we can’t think of much beyond the scientific facts, like “it pumps blood,” because our personal experience is always held to be of secondary importance to what we’ve been told to know, and therefore what to think.
So, if I ask you now “what is time?” looking for your experience of time, rather than the scientific definition of time, what might it be? So I ask you, what is time?
Go ahead, take your time.

Time is not separate from you, and as you are present, time does not go away.

This should just hammer it home for you. While you are here in this life, time is not separate from you—it’s your time—it’s not clock time, it’s not a stream of time flowing past you, its not a static road that you travel, because it is nothing other than you—your being here. So time and being are the same—the “is” between them is merely saying these two concepts mean exactly the same thing, as the sentence: “That is James” means, when you are pointing your finger at me.
So the takeaway is: there is no ‘Time’, there is only your time and my time, and the time of all other manifested things. You don’t have to be real, the way we think Time is real, but you’re not nothing either. You are being-time: manifested forms of time that we experience as our being here.
So that is Dogen’s assertion first quoted by the OP. But did you notice that if that is what time is, then there is nothing for us to move through, and nothing that moves past us? We ‘flow´ through our ‘selves’—our time, but not through time ‘itself’ because there is no such thing. Thats why Dogen says:

Birth is an expression complete this moment. Death is an expression complete this moment.”

We flow through our being, the way a play flows through its script—in its own time. But our being is always complete now—it can’t come to be, or cease to be in the way scientists would frame it as a passage of events over ‘Time’.
So now, you are probably lost in Space, not knowing what to think. So don’t think. Pay attention to what is right now in each moment. As Dogen points out:

Each moment is all being, is the entire world. Reflect now whether any being or any world is left out of the present moment.

What is a moment? Don’t fall back into thinking about clock-time! I prefer to use the word “vignette” because when I clearly  attend to what is, I notice that there is always a history hanging about—the ‘causes’ and ‘conditions’, seasoned with a bit of serendipity, that ‘brought me’ metaphorically speaking, to now. But its just history, a story about how I got here, and it’s just a story, because it isn’t still happening. In fact—the fact of what I experience—it isn’t still happening, and there isn’t any ‘Time’ in which it can be hiding out! This moment is all there is. But this moment—this Now—is not mine alone.
But there is more! My time is still unfolding—because I’m still here. So there is an expectation in this moment of still more ‘to come’—it’s another story, perhaps a dream, or just a job I ‘have’ to get done. Or maybe its a refusal to accept what is, and a story of a victim is in it’s place in my dream.
And then I notice that the causes and conditions are not mine alone, but entail and are indicative of other vignettes, other being-times, intricately woven into this moment now, because mine is not the only vignette playing out. As Dogen says:

In essence, all things in the entire world are linked with one another as moments. Because all moments are the time-being, they are your time-being.

This now—this moment—contains all the vignettes of every ‘thing’ and every ‘body’ all in this intricately woven now. And what ‘was’ are just stories, and what ‘will be’ are just dreams, because there isn’t ‘what is past’, and there isn’t ‘what will be’, there is just now, whole and complete. Nothing real ‘in and of itself’, but much more than the back story, and much more than the dream of what is to become, it’s what appears to be, now.
This is why Dogen says:

They are like winter and spring. You do not call winter the beginning of spring, nor summer the end of spring.

When I am ‘in’ (experiencing) Winter, I call it “Winter,” not “Spring,” and not “the “beginning of Spring.” This doesn’t mean that there are not causes and conditions now that may mature as the being of “Spring,” but when it is Spring, I call it “Spring,” and not the “end of Winter,” because that is just a story I tell myself about what was the case once upon a time.
There is no moment of transition for events to happen in. There is only this, now, and nothing else (remembering that “this” is a woven whole of every being-time all at once this).
So, “Winter,” in our habitual and shared way of seeing things in this Sahā world, comes before Spring, but never will you be in Winter while you are in Spring, nor will you ever be in a moment when there is a transition from one to another, for that moment can be neither.
And none of this stops anyone from weaving stories of cause and effects, natural laws to be followed by things, and those saving graces of ‘chance’ and ‘very long periods of timé, and it works to a certain point, allowing us to note tendencies and habits, allowing us to predict the weather, or how long a computer memory chip might take to respond to a query about its contents. That is, until we pay attention to what is truly present now and we cannot find what was and what might be fully present too.
Even scientists today no longer believe that Time is a thing.

user43: This idea is elaborated in Dogen's work called "Uji" (The Time-Being).
Here I will paste some bits and pieces:

Time itself is being, and all being is time.
Each moment is all being, is the entire world. Reflect now whether any being or any world is left out of the present moment.
In essence, all things in the entire world are linked with one another as moments. Because all moments are the time-being, they are your time-being.
Time is not separate from you, and as you are present, time does not go away.
Do not think that time merely flies away. Do not see flying away as the only function of time. If time merely flies away, you would be separated from time.
The time-being has the quality of flowing. So-called today flows into tomorrow.
You may suppose that time is only passing away, and not understand that time never arrives.
People only see time's coming and going, and do not thoroughly
understand that the time-being abides in each moment.
Do not think flowing is like wind and rain moving from east to west. The entire world is not unchangeable, is not immovable. It flows. Flowing is like spring. Spring with all its numerous aspects is called flowing. When spring flows there is nothing outside of spring. Study this in detail. Spring invariably flows through spring. Although flowing itself is not spring, flowing occurs throughout spring. Thus, flowing is completed at just this moment of spring. Examine this thoroughly, coming and going. In your study of flowing, if you imagine the objective to be outside yourself and that you flow and move through hundreds and thousands of worlds, for hundreds, thousands, and myriads of eons, you have not devotedly studied the buddha way.

What does this all mean? It means there is no hidden essence or identity that  would pass from the past into the future. When milk goes sour and "turns into" yogurt, or firewood burns out and "turns into" ash, or spring ends and summer starts, or "a person dies" - we habitually assume that something, some entity, stays itself throughout all phases and gets transferred from point A to point B to point C. However in reality there is no such thing. Identity is our imputation.
The young person, the old person, and the corpse are not the same entity - they are like the dominos falling in succession, like a moving wave. Similarly, the spring and summer are not the same entity, they are phases of flowing like the dominos in a chain.
Entire world is flowing like that, and most importantly the illusion that "I am staying the same as the time flows" or "I am moving through time while staying myself" - is the illusion of self. Our mind and our experience is part of the flow.
This is why, in Genjokoan:

It is a custom in Buddhism not to say that life turns into death. This is why we call it “unborn”. And it is an established Buddhist teaching since Gautama Buddha that death does not turn into life. This is why we call it “undying”. Life is an instantaneous situation, and death is also an instantaneous situation.


-1: <p><a href="http://www.thezensite.com/ZenTeachings/Dogen_Teachings/GenjoKoan8.htm" rel="nofollow noreferrer">Genjokoan</a> says</p>
<blockquote>
<p>Birth is an expression complete this moment. Death is an expression
complete this moment. They are like winter and spring. You do not call
winter the beginning of spring, nor summer the end of spring.</p>
</blockquote>
<p>Dogen says here that spring is not after winter, but there is still &quot;before&quot; and &quot;after&quot;, which is included in spring, and spring is independent of them. etc.</p>
<hr />
<p>If not the beginning of spring, what is before spring? Not winter.</p>
<hr />
<p>And if - likewise - the end of life is discontinuous with the present, does that mean life does not end when I only exist in the present?</p>
 19480: <p>Dogen is said to have said:</p>
<blockquote>
<p>Time itself is being, and all being is time.
But what does “is” mean, and how does it help form the answer being searched for by the OP?</p>
</blockquote>
<p>In the question, the OP interprets what Dogen said, in the text that the OP quoted, as meaning:</p>
<blockquote>
<p>Dogen says here that spring is not after winter, but there is still &quot;before&quot; and &quot;after&quot;, which is included in spring, and spring is independent of them. etc.</p>
</blockquote>
<p>But Dogen said:</p>
<blockquote>
<p>Birth is an expression complete this moment. Death is an expression complete this moment. They are like winter and spring. You do not call winter the beginning of spring, nor summer the end of spring.</p>
</blockquote>
<p>Lets deal with the first two assertions, and leave the metaphor for a moment. In the quote from Dogen’s “Uji,” there is the line:</p>
<blockquote>
<p>Time is not separate from you, and as you are present, time does not go away.</p>
</blockquote>
<p>We are so used to being told what to think, we have forgotten what it means to be. I like to ask of others, “Today, we know that the heart pumps blood, but before humans invented the water pump, what was the heart for?”</p>
<p>Of course, if we give it some time, and don’t just shut the question out of our thoughts, we all know what the heart is for—and it’s not to be a pump. Why? Because before we were told what it was, we all could experience it ourselves—and we still do. It’s just that when we are confronted today with a question, we can’t think of much beyond the scientific facts, like “it pumps blood,” because our personal experience is always held to be of secondary importance to what we’ve been told to know, and therefore what to think.</p>
<p>So, if I ask you now “what is time?” looking for your experience of time, rather than the scientific definition of time, what might it be? So I ask you, what is time?</p>
<p>Go ahead, take your time.</p>
<blockquote>
<p>Time is not separate from you, and as you are present, time does not go away.</p>
</blockquote>
<p>This should just hammer it home for you. While you are here in this life, time is not separate from you—it’s your time—it’s not clock time, it’s not a stream of time flowing past you, its not a static road that you travel, because it is nothing other than you—your <em>being</em> here. So time and being are the same—the “is” between them is merely saying these two concepts mean exactly the same thing, as the sentence: “That is James” means, when you are pointing your finger at me.</p>
<p>So the takeaway is: there is no ‘Time’, there is only your time and my time, and the time of all other manifested things. You don’t have to be real, the way we think Time is real, but you’re not nothing either. You are being-time: manifested forms of time that we experience as our being here.</p>
<p>So that is Dogen’s assertion first quoted by the OP. But did you notice that if that is what time is, then there is nothing for us to move through, and nothing that moves past us? We ‘flow´ through our ‘selves’—our time, but not through time ‘itself’ because there is no such thing. Thats why Dogen says:</p>
<blockquote>
<p>Birth is an expression complete this moment. Death is an expression complete this moment.”</p>
</blockquote>
<p>We flow through our being, the way a play flows through its script—in its own time. But our being is always complete now—it can’t come to be, or cease to be in the way scientists would frame it as a passage of events over ‘Time’.</p>
<p>So now, you are probably lost in Space, not knowing what to think. So don’t think. Pay attention to what is right now in each moment. As Dogen points out:</p>
<blockquote>
<p>Each moment is all being, is the entire world. Reflect now whether any being or any world is left out of the present moment.</p>
</blockquote>
<p>What is a moment? Don’t fall back into thinking about clock-time! I prefer to use the word “vignette” because when I clearly  attend to what is, I notice that there is always a history hanging about—the ‘causes’ and ‘conditions’, seasoned with a bit of serendipity, that ‘brought me’ metaphorically speaking, to now. But its just history, a story about how I got here, and it’s just a story, because it isn’t still happening. In fact—the fact of what I experience—it isn’t still happening, and there isn’t any ‘Time’ in which it can be hiding out! This moment is all there is. But this moment—this Now—is not mine alone.</p>
<p>But there is more! My time is still unfolding—because I’m still here. So there is an expectation in this moment of still more ‘to come’—it’s another story, perhaps a dream, or just a job I ‘have’ to get done. Or maybe its a refusal to accept what is, and a story of a victim is in it’s place in my dream.</p>
<p>And then I notice that the causes and conditions are not mine alone, but entail and are indicative of other vignettes, other being-times, intricately woven into this moment now, because mine is not the only vignette playing out. As Dogen says:</p>
<blockquote>
<p>In essence, all things in the entire world are linked with one another as moments. Because all moments are the time-being, they are your time-being.</p>
</blockquote>
<p>This now—this moment—contains all the vignettes of every ‘thing’ and every ‘body’ all in this intricately woven now. And what ‘was’ are just stories, and what ‘will be’ are just dreams, because there isn’t ‘what is past’, and there isn’t ‘what will be’, there is just now, whole and complete. Nothing real ‘in and of itself’, but much more than the back story, and much more than the dream of what is to become, it’s what appears to be, now.</p>
<p>This is why Dogen says:</p>
<blockquote>
<p>They are like winter and spring. You do not call winter the beginning of spring, nor summer the end of spring.</p>
</blockquote>
<p>When I am ‘in’ (experiencing) Winter, I call it “Winter,” not “Spring,” and not “the “beginning of Spring.” This doesn’t mean that there are not causes and conditions now that may mature as the <em>being</em> of “Spring,” but when it is Spring, I call it “Spring,” and not the “end of Winter,” because that is just a story I tell myself about what was the case once upon a time.</p>
<p>There is no moment of transition for events to happen in. There is only this, now, and nothing else (remembering that “this” is a woven whole of every being-time all at once this).</p>
<p>So, “Winter,” in our habitual and shared way of seeing things in this Sahā world, comes before Spring, but never will you be in Winter while you are in Spring, nor will you ever be in a moment when there is a transition from one to another, for that moment can be neither.</p>
<p>And none of this stops anyone from weaving stories of cause and effects, natural laws to be followed by things, and those saving graces of ‘chance’ and ‘very long periods of timé, and it works to a certain point, allowing us to note tendencies and habits, allowing us to predict the weather, or how long a computer memory chip might take to respond to a query about its contents. That is, until we pay attention to what is truly present now and we cannot find what was and what might be fully present too.</p>
<p>Even scientists today no longer believe that Time is a thing.</p>
 43: <p>This idea is elaborated in Dogen's work called &quot;Uji&quot; (The Time-Being).<br />
Here I will paste some bits and pieces:</p>
<blockquote>
<p>Time itself is being, and all being is time.</p>
<p>Each moment is all being, is the entire world. Reflect now whether any being or any world is left out of the present moment.</p>
<p>In essence, all things in the entire world are linked with one another as moments. Because all moments are the time-being, they are your time-being.</p>
<p>Time is not separate from you, and as you are present, time does not go away.</p>
<p>Do not think that time merely flies away. Do not see flying away as the only function of time. If time merely flies away, you would be separated from time.</p>
<p>The time-being has the quality of flowing. So-called today flows into tomorrow.<br />
You may suppose that time is only passing away, and not understand that time never arrives.<br />
People only see time's coming and going, and do not thoroughly
understand that the time-being abides in each moment.</p>
<p>Do not think flowing is like wind and rain moving from east to west. The entire world is not unchangeable, is not immovable. It flows. Flowing is like spring. Spring with all its numerous aspects is called flowing. When spring flows there is nothing outside of spring. Study this in detail. Spring invariably flows through spring. Although flowing itself is not spring, flowing occurs throughout spring. Thus, flowing is completed at just this moment of spring. Examine this thoroughly, coming and going. In your study of flowing, if you imagine the objective to be outside yourself and that you flow and move through hundreds and thousands of worlds, for hundreds, thousands, and myriads of eons, you have not devotedly studied the buddha way.</p>
</blockquote>
<p>What does this all mean? It means there is no hidden essence or identity that  would pass from the past into the future. When milk goes sour and &quot;turns into&quot; yogurt, or firewood burns out and &quot;turns into&quot; ash, or spring ends and summer starts, or &quot;a person dies&quot; - we habitually assume that something, some entity, stays itself throughout all phases and gets transferred from point A to point B to point C. However in reality there is no such thing. Identity is our imputation.</p>
<p>The young person, the old person, and the corpse are not the same entity - they are like the dominos falling in succession, like a moving wave. Similarly, the spring and summer are not the same entity, they are phases of flowing like the dominos in a chain.</p>
<p>Entire world is flowing like that, and most importantly the illusion that &quot;I am staying the same as the time flows&quot; or &quot;I am moving through time while staying myself&quot; - is the illusion of self. Our mind and our experience is part of the flow.</p>
<p>This is why, in Genjokoan:</p>
<blockquote>
<p>It is a custom in Buddhism not to say that life turns into death. This is why we call it “unborn”. And it is an established Buddhist teaching since Gautama Buddha that death does not turn into life. This is why we call it “undying”. Life is an instantaneous situation, and death is also an instantaneous situation.</p>
</blockquote>
