natural way only from .another perception, just as a motion can come in a natural way only from a motion.
24. It is evident from this that if we were to have nothing distinctive, or so to speak prominent, and of a higher flavour in our perceptions, we should be in a continual state of stupor. This is the condition of monads which are wholly bare.
25. We see that nature has given to animals heightened perception, s, having provided them with organs which collect numerous rays of light or numerous waves of air and thus make them more effective in their combination. Something similar to this takes place in the case of smell, in that of taste and of touch, and perhaps in many other senses which are unknown to us. I shall have occasion very soon to explain how that which occurs in the soul represents that which goes on in the sense organs.
26. The memory furnishes a sort of consecutiveness which imitates reason but is to be distinguished from it. We see that animals when they have the perception of something which they notice and. of which they have had a similar previous perception, are led by the representation of their memory to expect that which was associated in the preceding perception, and they come to have feelings like those which they had before. For instance, if a stick be shown to a dog, he remembers the pain which it has caused him and he whines or runs away.
27. The vividness of the picture, which comes to him or moves him, is derived either from the magnitude or from the number of the previous perceptions. For, oftentimes, a strong impression brings about, all at once, the same effect as a long-continued habit or as a great many reiterated, moderate perceptions.
28. Men act in like manner as animals, in so far as the sequence of their perceptions is determined only by the law of memory, resembling the empirical physicians who practice simply, without any theory, and we are empiricists in three-fourths of our actions. For instance, when we expect that there will be daylight tomorrow, we do so empirically, because it has always happened so up to the present time. It is only the astronomer who uses his reason in making such an affirmation.
29. But the knowledge of eternal and necessary truths is that which distinguishes us from mere animals and gives us reason and the sciences, thus raising us to a knowledge of ourselves and of God. This is what is called in us the Rational Soul or the Mind.
30. It is also through the knowledge of necessary truths and through abstractions from them that we come to perform Reflective Acts, which cause us to think of what is called the I, and to decide that this or that is within us. it is thus, that in thinking upon ourselves we think of being, of substance, of the simple and compound, of a material thing and of God himself, conceiving that what is limited in us is in him without limits. These reflective acts furnish the principal objects of our reasonings.
31. Our reasoning is based upon two great principles: first, that of contradiction, by means of which we decide that to be false which involves contradiction and that to be true which contradicts or is opposed to the false.
32. And second, the principle of sufficient reason, in virtue of which we believe that no fact can be real or existing and no statement true unless it has a sufficient reason why it should be thus and not otherwise. Most frequently, however, these reasons cannot be known by us.
33. There are also two kinds of truths: those of reasoning and those of fact. The truths of reasoning are necessary, and their opposite is impossible. Those of fact, however, are contingent, and their opposite is possible. When a truth is necessary, the reason can be found by analysis in resolving it into simpler ideas and into simpler truths until we reach those which are primary.
34. It is thus that with mathematicians the speculative theorems and the practical canons are reduced by analysis to definitions, axioms, and postulates.
35. There are finally simple ideas of which no definition can be given. There are also the axioms and po