I obtained the requisite official permission, and opened the course at the Ecole Pratique under the best auspices. The lectures were thronged from the beginning, and the interest by no means abated as the weeks rolled on. Enthusiastic myself, I possessed in no small degree the gift of communicating (on all ordinary subjects) my enthusiasm to others. I aimed less at imparting solid instruction to my pupils than at impressing their imagination by a series of skilfully arranged effects. My experiments, therefore, were governed by dramatic unity, rarely sought in the confused and arid expositions of official professors. Now I led my auditors into the inmost laboratories of Nature, and revealed, in plant and animal, the fine affinities that regulated her processes of nutrition. Now I traced some delicate nervous filament from the spinal column of the amphioxus to the cerebral hemisphere of the mammifer. Now I disclosed the ramifying canals in the vast system of circulation, mounting from the spongy network of the mollusk and the sluggish lymphatic of the reptile to the brilliant, bounding arteries of the double-hearted vertebrates. And always, beyond the last disclosure, after the most complete revelation, I hinted at something yet to come, some higher, unveiled mystery, to which all this grand series was but the prelude. As a priest who volubly initiates the neophytes into the service of the temple, but points in silence to the inner court containing the Deity for whom the service is performed, so I, after the most magnificent display of animal life, silently indicated a concealed hereafter, a culmination in the human body, hitherto withheld from our curious gaze. I thus strove to suggest an ideal, left for a time incomplete; to foster an impetuous impatience, that, stimulated by the great acquisitions of the past, should reach forward irresistibly for the greater prize of the future. I trusted that among all my auditors would be found one that should divine the cipher, and quicken over its subtle secret--one intellect, that, carried unconsciously along the current of my thought, should finally arrive at my unrevealed goal.