Any one may easily observe this in his own thoughts, who will take the pains to reflect on them. Secondly, we shall not be so much surprised that this is done in us with so little notice, if we consider how the facility which we get of doing things, by a custom of doing, makes them often pass in us without our notice. Habits, especially such as are begun very early, come at last to produce actions in us, which often escape our observation. Men that, by custom, have got the use of a by-word, do almost in every sentence pronounce sounds which, though taken notice of by others, they themselves neither hear nor observe. And therefore it is not so strange, that our mind should often change the idea of its sensation into that of its judgment, and make one serve only to excite the other, without our taking notice of it.
Perception puts the difference between animals and vegetables.
This faculty of perception seems to me to be, that which puts the distinction betwixt the animal kingdom and the inferior parts of nature. All which is done without any sensation in the subject, or the having or receiving any ideas. Perception in all animals. So that the wisdom and goodness of the Maker plainly appear in all the parts of this stupendous fabric, and all the several degrees and ranks of creatures in it. According to their condition.