7. Or rather, before dealing with these, it is right that we should mark the skilled workmanship of nature in the actual construction of the body. For as that which is hard and resistent does not admit the action of the senses (as we may see in the instance of our own bones, and in that of plants in the ground, where we remark indeed a certain form of life in that they grow and receive nourishment, yet the resistent character of their substance does not allow them sensation), for this reason it was necessary that some wax-like formation, so to say, should be supplied for the action of the senses, with the faculty of being impressed with the stamp of things capable of striking them, neither becoming confused by excess of moisture (for the impress would not remain in moist substance), nor resisting by extraordinary solidity (for that which is unyielding would not receive any mark from the impressions), but being in a state between softness and hardness, in order that the living being might not be destitute of the fairest of all the operations of nature—I mean the motion of sense.