This faculty is perfect of its kind from the outset; otherwise the insect would have no posterity. Time adds nothing to it and takes nothing from it. Such as it was for a definite species, such it is to-day and such it will remain, perhaps the most settled zoological characteristic of them all. It is not free nor conscious in its practice, any more than is the faculty of the stomach for digestion or that of the heart for pulsation. The phases of its operations are predetermined, necessarily entailed one by another; they suggest a system of clockwork wherein one wheel set in motion brings about the movement of the next. This is the mechanical side of the insect, the fatum, the only thing that is able to explain the monstrous illogicality of a Pelopæus misled by my artifices. Is the Lamb when it first grips the teat a free and conscious agent, capable of improvement in its difficult art of taking nourishment? The insect is no more capable of improvement in its art, more difficult still, of giving nourishment. But, with its hide-bound science ignorant of itself, pure instinct, if it stood alone, would leave the insect unarmed in the perpetual conflict of circumstances. No two moments in time are identical; though the background remain the same, the details change; the unexpected rises on every side. In this bewildering confusion, a guide is needed to seek, accept, refuse and select; to show preference for this and indifference to that; to turn to account, in short, anything useful that occasion may offer. This guide the insect undoubtedly possesses, to a very manifest degree. It is the second province of its mentality. Here it is conscious and capable of improvement by experience. I dare not speak of this rudimentary faculty as intelligence, which is too exalted a title: I will call it discernment. The insect, in exercising its highest gifts, discerns, differentiates between one thing and another, within the sphere of its craft, of course; and that is about all. So long as we confound acts of pure instinct and acts of discernment under the same head, we shall fall back into those endless discussions which embitter controversy without bringing us one step nearer to the solution of the problem. Is the insect conscious of what it does? Yes and no. No, if its action falls within the domain of instinct; yes, if the action falls within that of discernment. Are the habits of an insect capable of modification? No, decidedly not, if the habit in question belongs to the province of instinct; yes, if it belongs to that of discernment. Let us state this fundamental distinction more precisely with the aid of a few examples.