Beings essentially different by their natural organization, by the modifications they experience, by the habits they contract, by the opinions they acquire, must of necessity think differently. His temperament, as we have seen, decides the mental qualities of man: this temperament itself is diversely modified in him: from whence it consecutively follows, his imagination cannot possibly be the same; neither can it create to him the same images. Each individual is a connected whole, of which all the parts have a necessary correspondence. Different eyes must see differently, must give extremely varied ideas of the objects they contemplate, even when these objects are real. What, then, must be the diversity of these ideas, if the objects meditated upon do not act upon the senses? Mankind have pretty nearly the same ideas, in the gross, of those substances that act upon his organs with vivacity; he is sufficiently in unison upon some qualities which he contemplates very nearly in the same manner; I say, very nearly, because the intelligence, the notion, the conviction of any one proposition, however simple, however evident, however clear it may be supposed, is not, nor cannot be, strictly the same, in any two men. Indeed, one man not being another man, the first cannot, for example, have rigorously and mathematically the same notion of unity as the second; seeing that an identical effect cannot be the result of two different causes. Thus, when men are in accord in their ideas, in their modes of thinking, in their judgment, in their passions, in their desires, in, their tastes, their consent does not arise from their seeing or feeling the same objects precisely in the same manner, but pretty nearly; language is not, nor cannot be, sufficiently copious to designate the vast variety of shades, the multiplicity of imperceptible differences, which is to be found in their modes of seeing and thinking. Each man, then, has, to say thus, a language which is peculiar to himself alone, and this language is incommunicable to others. What harmony, what unison, then, can possibly exist between them, when they discourse with each other, upon objects only known to their imagination? Can this imagination in one individual ever be the same as in another? How can they possibly understand each other, when they assign to those objects qualities that can only be attributed to the particular manner in which their brain is affected.