of its cornea, the different density of its three humours, the form of its lens, the blackness of its choroid, the sensitiveness of its retina, the contracting power of its pupil, and its muscular system, accurately calculated according to those laws. But those motives acted before they were apprehended; it is not otherwise, however contradictory it may sound. For here is the transition of the physical into the metaphysical. But the latter we have already recognised in the will; therefore we must see that the will which extends an elephant s trunk towards an object is the same will which has also called it forth and formed it, anticipating objects.
It is in conformity with this that in the investigation of organised nature we are entirely referred to final causes, everywhere seek for these and explain everything from them. The efficient causes, on the contrary, here assume only a quite subordinate position as the mere tools of the final causes, and, just as in the case of the voluntary movement of the limbs, which is confessedly effected by external motives, they are rather assumed than pointed out. In explaining the physiological functions we certainly look about for the efficient causes, though for the most part in vain; but in explaining the origin of the parts we again look for them no more, but are satisfied with the final causes alone. At the most we have here some such general principle as that the larger the part is to be the stronger must be the artery that conducts blood to it; but of the actually efficient causes which bring about, for example, the eye, the ear, the brain, we know absolutely nothing. Indeed, even in explaining the mere functions the final cause is far more important and more to the point than the efficient; therefore, if the former alone is known we are instructed and satisfied with regard to the principal matter, while, on the other hand, the efficient cause alone helps us little. For example, if we really knew the efficient cause of the circulation of the blood, as we do not, but still seek it, this would help us little unless
