"Weak and narrow," he says, "are the powers implanted in the limbs of men; many the woes that fall on them and blunt the edge of thought; short is the measure of the life in death through which they toil; then are they borne away, like smoke they vanish into air, and what they dream they know is but the little each hath stumbled on in wandering about the world; yet boast they all that they have learned the whole--vain fools! for what _that_ is, no eye hath seen, no ear hath heard, nor can it be conceived by mind of man. Thou, then, since thou hast fallen to this place, shalt know no more than human wisdom may attain. "But, O ye gods, avert the madness of those babblers from my tongue, and cause the stream of holy words to issue from my hallowed lips. And thou, great Muse of Memory, maiden with the milk-white arms, I pray to thee to teach me things that creatures of a day may hear. Come from the House of Holiness, and bring to me her harnessed car." Here we see plainly set forth the impossibility of mortal, fallen intellects attaining to a perfect knowledge of the Universe, the impiety of seeking such knowledge, or pretending to have found it; and, at the same time, the limitations under which true science remains within the reach of human beings. How this science may be reached, he tells us in some memorable lines, probably supposed to issue from the lips of the Muse whom he invokes: "But come, search diligently, and discover what is clear in every realm of sense, ... check the conviction of thy senses, and judge by reason what is evident in every case."