For the better understanding of which definition, we must consider, first, that although Sense and Memory of things, which are common to man and all living creatures, be knowledge, yet because they are given us immediately by nature, and not gotten by ratiocination, they are not philosophy. Secondly, seeing Experience is nothing but memory; and Prudence, or prospect into the future time, nothing but expectation of such things as we have already had experience of, Prudence also is not to be esteemed philosophy. By RATIOCINATION, I mean _computation_. Now to compute, is either to collect the sum of many things that are added together, or to know what remains when one thing is taken out of another. _Ratiocination_, therefore, is the same with _addition_ and _substraction_; and if any man add _multiplication_ and _division_, I will not be against it, seeing multiplication is nothing but addition of equals one to another, and division nothing but a substraction of equals one from another, as often as is possible. So that all ratiocination is comprehended in these two operations of the mind, addition and substraction. [Sidenote: Ratiocination of the Mind.] 3. But how by the _ratiocination_ of our mind, we add and substract in our silent thoughts, without the use of words, it will be necessary for me to make intelligible by an example or two. If therefore a man see something afar off and obscurely, although no appellation had yet been given to anything, he will, notwithstanding, have the same idea of that thing for which now, by imposing a name on it, we call it _body_. Again, when, by coming nearer, he sees the same thing thus and thus, now in one place and now in another, he will have a new idea thereof, namely, that for which we now call such a thing _animated_. Thirdly, when standing nearer, he perceives the figure, hears the voice, and sees other things which are signs of a rational mind, he has a third idea, though it have yet no appellation, namely, that for which we now call anything _rational_. Lastly, when, by looking fully and distinctly upon it, he conceives all that he has seen as one thing, the idea he has now is compounded of his former ideas, which are put together in the mind in the same order in which these three single names, _body_, _animated_, _rational_, are in speech compounded into this one name, _body-animated-rational_, or _man_. In like manner, of the several conceptions of _four sides, equality of sides, and right angles_, is compounded the conception of a _square_. For the mind may conceive a figure of four sides without any conception of their equality, and of that equality without conceiving a right angle; and may join together all these single conceptions into one conception or one idea of a square. And thus we see how the conceptions of the mind are compounded. Again, whosoever sees a man standing near him, conceives the whole idea of that man; and if, as he goes away, he follow him with his eyes only,