Since, of the two senses of _Sight_ and _Touch_, that of _Sight_,--as far, at least, as we are able, by intellectual analysis at present to discover its original sensations,--is more simple, and more analogous to the senses before considered, I should be inclined, on these accounts, to proceed to the consideration of it, previously to any inquiry into the sense of Touch. But this order, though unquestionably the more regular, if we had to consider only the original sensations of each organ, would be attended with great inconvenience in considering their subsequent modified sensations; since those of Vision depend, in a very great degree, on the _prior_ affections of _Touch_, with the nature of which, therefore, it is necessary for you to be acquainted in the first place. I am aware, indeed, that, in considering even _Touch_, I may sometimes find it necessary to refer, for illustration to the phenomena of _Vision_, though these have not been considered by us, and must, therefore, for the time, be taken upon trust. But when phenomena are at all complicated, such occasional anticipations are absolutely unavoidable. Sensation, indeed, says Aristotle, is a _straight line_, while intellect is a _circle_,--Αἴσθησις γραμμὴ, νοῦς κύκλος,--or to use the paraphrastic translation of Cudworth, in his treatise on Immutable Morality, “Sense is of that which is without. Sense wholly gazes and gads abroad; and, therefore, doth not know and comprehend its object, because it is different from it. Sense is a line, the mind is a circle. Sense is like a line, which is the flux of a point running out from itself; but intellect like a circle, that keeps within itself.”[82] That sense is not a circle is, indeed, true, since it terminates in a point; but far from being a _straight_ line, it is one of the most perplexing of _curves_, and is crossed and cut by so many other curves,--into many of which it flows, and unites with them completely,--that when we arrive at the extremity of the line, it is almost impossible for us to determine with accuracy what _curve_ it is, which, in the strange confusion of our diagram, we have been attempting to trace from its initial point. I proceed, then, to the consideration of the phenomena of the sense of TOUCH.