Helmholtz himself, however, points out that the defects of the eye are "all so counteracted, that the inexactness of the image which results from their presence very little exceeds, under ordinary conditions of illumination, the limits which are set to the delicacy of sensation by the dimensions of the retinal cones;" that "the adaptation of the eye to its function is most complete, and is seen in the very limits which are set to its defects." In fact, were the eye more perfect as an instrument of optical precision, it would be less perfect as an eye. Its absolute defects are practical merits. To be a useful eye it must be neither a perfect telescope nor a perfect microscope, but a something which can readily serve many purposes, and which can be supplemented by many instruments. The delicate finish of a razor renders it unfit for cutting wood. All man's senses and organs are inferior to those possessed by some of the lower animals, but the inferiority is of a kind which is a real and vast advantage. It is of a kind which allows them to be put to a greater variety of uses than could more perfect senses and organs. It is the very condition of their capacity to be utilised in manifold directions by an inventive and progressive reason. Further, no man can see at all merely with a so-called perfect optical instrument. He must have in addition the imperfect instrument, composed of a soft, watery, animal substance, and designated the eye. There is that in the eye which immeasurably transcends all mere physics and chemistry, all human mechanism and contrivance; there is life; there is vision. NOTE XXXIV., page 252. EPICUREAN DILEMMA.