user8157: The well-known yet often differently translated opening verses of the Dhamma use the Pali words "mano" and "manasa", as follows:

Manopubbaṅgamā dhammā,
manoseṭṭhā manomayā;
Manasā ce paduṭṭhena,
bhāsati vā karoti vā;
Tato naṃ dukkhamanveti,
cakkaṃva vahato padaṃ.
Manopubbaṅgamā dhammā,
manoseṭṭhā manomayā;
Manasā ce pasannena,
bhāsati vā karoti vā;
Tato naṃ sukhamanveti,
chāyāva anapāyinī

What do the Pali words "mano" and "manasa" specify refer to & why are they used in Dhammapada verses 1 & 2? 

user-1: In simple words (not writing this for bounty)
1.)Meaning :
Mano & Mansa refer to same word ,'MIND' but meaning .
Mano means ,"Only Mind is"  and
Mansa means ," by/through/with Mind ".
2.)Why? :
To indicate that only mind (within our body) is a leader of every tiny bit of sorrowness & happiness . If behaviour is with corrupted mind ,sorrowness arises & if behaviour is through good-will mind ,happiness arises.
Learner is mind ,teacher is mind .
Mind sees itself ,mind talks to itself that's why mind punishes itself &  awards itself.
Explanation ::
As for me & every being on earth with Mind...
Eye signals or Sensory signals from outside world(for eyeless beings) develop a sense of understanding either through image inside brain or through senses. This whole process ( & all the other interacting electric signals too) within our body  is called Mind .
PAY ATTENTION PAL.
This Mind has few in-built properties of aversion & craving due to Ignorance towards lust ,anger ,laziness etc . But certain fewones become able to change this behaviour pattern , become detached to world while living alongside world.
When behaviour is done with detached(good-will) Mind i.e. process of interacting electric signals within body produces
no clinging effect OR attachement to anything , eternal happiness arises.
But
When behaviour is done with Ignorance , only suffering arises.
---------- :)
Whatever we see or feel , ultimately it's image or sense is developed in Mind within body & every reaction is done by Mind (i.e. by the electric signal process within body) w.r.t. those images/ senses.
So Mind sees itself , talks to itself & when process is corrupted due to Ignorance Punishement in form of Suffering occurs . When process is clean & of good-will( detached one) ,gifts in form of satisfied_happiness arises.
Why Suffering arises?
Cause within our body we want to remain calm ,secure ,peace ,satisfied ,etc. but process is completely corrupted & hence what 'we want ' is not happening so process reacts AGAINST itself because ,'we want' is also a part of process. When our mind is against itself ,it feels like agitation ,bad ,sorrow ,depression etc.
Why gifts of happiness?
Cause No-one is against anyone.Mind is completely clean. Calm , Secure ,peace ,pre-satisfied etc. are now the inbuilt properties of Mind. So Mind does not oppose itself. That keeps enlightened one in equanimity.
That's why, Mano pubbangma dhamma ,...., mansa che ...
Phew! That was a lot of Explanation. It's my 2nd time to explain this process. 1st was when I was serving for free in a Sikh Temple.At that time I tried to explain this process to a teacher of intermediate class students.He couldn't understand... :)

user43: As to the word manas, Thrangu Rinpoche said (paraphrasing): 

All mental events—all thoughts, memories and anticipation of the future with all its emotions of happiness, sadness, excitement, and frustration takes place in the manas. It is the manas which differentiates and thinks and makes judgements about the perception. After the eye, ear, nose, tongue and tactile consciousness perceives an object, the manas judges the sensory perception with thoughts. 

So the word manas here is used to drive home the idea that it is our mind -- in the sense of our outlook, our way of seeing and interpretation -- is what creates our reality.
In Tibetan Buddhism they have this notion called "pure perception" or "sacred outlook". It's a practice of seeing everything as expression of Buddha-Nature, without a taint.
When we see the world with pure perception, there are no enemies of ours, no aggression is provoked in us, no anger, no antipathy. The reality of our perception is pure. Then our reactions are pure, our karma is pure, and it results in peace.
But when our perception is tainted, we see a different reality, we are in a different world. So naturally this world provokes very different reactions in us, which lead to trouble.
It is our outlook that defines our reality, our actions, and its results. 
This outlook is a state of mind.
This is what is meant here by the word manas.

If one speaks or acts out of an addled manas, dukkha follows him like the cart's wheel follows the ox's hoofprint.  
...  
If one speaks or acts out of a clear manas, sukha follows him like a shadow which never leaves.

Now, what exactly is addled/dirty manas and what is clear/pure manas?
Manas is not memory, it is only an organ of mental (inner, reflective) perception, thus supporting further interpretation and judgement - so how and why can it be dirty or clean?
Manas is exactly the part of mind where Upadana or Feeding occurs. Upadana is when we keep going over a certain idea or image or event, triggering our interpretation and emotional reaction again and again. As a result of this cyclic feeding, manas constantly keeps this idea "loaded", and presence of this idea affects or skews all new interpretation and judgment. 
So the dirty manas or dirty outlook is what happens when we feed on negative, selfish, aggressive, divisive thoughts.
And the pure manas is when we don't feed, don't maintain these tainting dharmas (known as klesha or asava). As a result we see things yathabhuta - as they are. Seeing things as they are leads to right action, and right action leads to the ending of suffering and to harmony and peace. 
This is why the subsequent verses of Dhammapada speak about (not) harboring offense and enmity, (not) dwelling on pleasant experiences, and eventually "vomiting all the asavas". These are examples of maintaining the dirty manas vs purifying it. 

8157: <p>The well-known yet often differently translated opening verses of the Dhamma use the Pali words "mano" and "manasa", as follows:</p>

<blockquote>
  <p><strong>Mano</strong>pubbaṅgamā dhammā,</p>
  
  <p><strong>mano</strong>seṭṭhā <strong>mano</strong>mayā;</p>
  
  <p><strong>Manasā</strong> ce paduṭṭhena,</p>
  
  <p>bhāsati vā karoti vā;</p>
  
  <p>Tato naṃ dukkhamanveti,</p>
  
  <p>cakkaṃva vahato padaṃ.</p>
  
  <p><strong>Mano</strong>pubbaṅgamā dhammā,</p>
  
  <p><strong>mano</strong>seṭṭhā <strong>mano</strong>mayā;</p>
  
  <p><strong>Manasā</strong> ce pasannena,</p>
  
  <p>bhāsati vā karoti vā;</p>
  
  <p>Tato naṃ sukhamanveti,</p>
  
  <p>chāyāva anapāyinī</p>
</blockquote>

<p>What do the Pali words "mano" and "manasa" specify refer to &amp; why are they used in Dhammapada verses 1 &amp; 2? </p>
 -1: <p>In simple words (not writing this for bounty)</p>
<p>1.)Meaning :<br />
Mano &amp; Mansa refer to same word ,'MIND' but meaning .<br />
Mano means ,&quot;Only Mind is&quot;  and<br />
Mansa means ,&quot; by/through/with Mind &quot;.</p>
<p>2.)Why? :<br />
To indicate that only mind (within our body) is a leader of every tiny bit of sorrowness &amp; happiness . If behaviour is with corrupted mind ,sorrowness arises &amp; if behaviour is through good-will mind ,happiness arises.</p>
<p>Learner is mind ,teacher is mind .<br />
Mind sees itself ,mind talks to itself that's why mind punishes itself &amp;  awards itself.</p>
<p>Explanation ::</p>
<p>As for me &amp; every being on earth with Mind...</p>
<p>Eye signals or Sensory signals from outside world(for eyeless beings) develop a sense of understanding either through image inside brain or through senses. This whole process ( &amp; all the other interacting electric signals too) within our body  is called Mind .</p>
<p>PAY ATTENTION PAL.</p>
<p>This Mind has few in-built properties of aversion &amp; craving due to Ignorance towards lust ,anger ,laziness etc . But certain fewones become able to change this behaviour pattern , become detached to world while living alongside world.</p>
<p>When behaviour is done with detached(good-will) Mind i.e. process of interacting electric signals within body produces
no clinging effect OR attachement to anything , eternal happiness arises.</p>
<p>But</p>
<p>When behaviour is done with Ignorance , only suffering arises.</p>
<p>---------- :)</p>
<p>Whatever we see or feel , ultimately it's image or sense is developed in Mind within body &amp; every reaction is done by Mind (i.e. by the electric signal process within body) w.r.t. those images/ senses.<br />
So Mind sees itself , talks to itself &amp; when process is corrupted due to Ignorance Punishement in form of Suffering occurs . When process is clean &amp; of good-will( detached one) ,gifts in form of satisfied_happiness arises.</p>
<p>Why Suffering arises?<br />
Cause within our body we want to remain calm ,secure ,peace ,satisfied ,etc. but process is completely corrupted &amp; hence what 'we want ' is not happening so process reacts AGAINST itself because ,'we want' is also a part of process. When our mind is against itself ,it feels like agitation ,bad ,sorrow ,depression etc.</p>
<p>Why gifts of happiness?<br />
Cause No-one is against anyone.Mind is completely clean. Calm , Secure ,peace ,pre-satisfied etc. are now the inbuilt properties of Mind. So Mind does not oppose itself. That keeps enlightened one in equanimity.</p>
<p>That's why, Mano pubbangma dhamma ,...., mansa che ...</p>
<p>Phew! That was a lot of Explanation. It's my 2nd time to explain this process. 1st was when I was serving for free in a Sikh Temple.At that time I tried to explain this process to a teacher of intermediate class students.He couldn't understand... :)</p>
 43: <p>As to the word manas, Thrangu Rinpoche said (paraphrasing): </p>

<blockquote>
  <p>All mental events—all thoughts, memories and anticipation of the future with all its emotions of happiness, sadness, excitement, and frustration takes place in the manas. It is the manas which differentiates and thinks and makes judgements about the perception. After the eye, ear, nose, tongue and tactile consciousness perceives an object, the manas judges the sensory perception with thoughts. </p>
</blockquote>

<p><strong>So the word manas here is used to drive home the idea that it is our mind -- in the sense of our outlook, our way of seeing and interpretation -- is what creates our reality.</strong></p>

<p>In Tibetan Buddhism they have this notion called "pure perception" or "sacred outlook". It's a practice of seeing everything as expression of Buddha-Nature, without a taint.</p>

<p>When we see the world with pure perception, there are no enemies of ours, no aggression is provoked in us, no anger, no antipathy. The reality of our perception is pure. Then our reactions are pure, our karma is pure, and it results in peace.</p>

<p>But when our perception is tainted, we see a different reality, we are in a different world. So naturally this world provokes very different reactions in us, which lead to trouble.</p>

<p>It is our outlook that defines our reality, our actions, and its results. </p>

<p>This outlook is a state of mind.</p>

<p>This is what is meant here by the word manas.</p>

<blockquote>
  <p>If one speaks or acts out of an addled manas, dukkha follows him like the cart's wheel follows the ox's hoofprint.  </p>
  
  <p>...  </p>
  
  <p>If one speaks or acts out of a clear manas, sukha follows him like a shadow which never leaves.</p>
</blockquote>

<p>Now, what exactly is addled/dirty manas and what is clear/pure manas?</p>

<p>Manas is not memory, it is only an organ of mental (inner, reflective) perception, thus supporting further interpretation and judgement - so how and why can it be dirty or clean?</p>

<p>Manas is exactly the part of mind where Upadana or Feeding occurs. Upadana is when we keep going over a certain idea or image or event, triggering our interpretation and emotional reaction again and again. As a result of this cyclic feeding, manas constantly keeps this idea "loaded", and presence of this idea affects or skews all new interpretation and judgment. </p>

<p>So the dirty manas or dirty outlook is what happens when we feed on negative, selfish, aggressive, divisive thoughts.</p>

<p>And the pure manas is when we don't feed, don't maintain these tainting dharmas (known as klesha or asava). As a result we see things yathabhuta - as they are. Seeing things as they are leads to right action, and right action leads to the ending of suffering and to harmony and peace. </p>

<p>This is why the subsequent verses of Dhammapada speak about (not) harboring offense and enmity, (not) dwelling on pleasant experiences, and eventually "vomiting all the asavas". These are examples of maintaining the dirty manas vs purifying it. </p>
