In support of his definitions, Lambert propounded a variety of problems to be solved, challenges flung out to science, though he proposed to seek the solution for himself. He inquired, for instance, whether the element that constitutes electricity does not enter as a base into the specific fluid whence our Ideas and Volitions proceed? Whether the hair, which loses its color, turns white, falls out, or disappears, in proportion to the decay or crystallization of our thoughts, may not be in fact a capillary system, either absorbent or diffusive, and wholly electrical? Whether the fluid phenomena of the Will, a matter generated within us, and spontaneously reacting under the impress of conditions as yet unobserved, were at all more extraordinary than those of the invisible and intangible fluid produced by a voltaic pile, and applied to the nervous system of a dead man? Whether the formation of Ideas and their constant diffusion was less incomprehensible than evaporation of the atoms, imperceptible indeed, but so violent in their effects, that are given off from a grain of musk without any loss of weight. Whether, granting that the function of the skin is purely protective, absorbent, excretive, and tactile, the circulation of the blood and all its mechanism would not correspond with the transsubstantiation of our Will, as the circulation of the nerve fluid corresponds to that of the Mind? Finally, whether the more or less rapid affluence of these two real substances may not be the result of a certain perfection or imperfection of organs whose conditions require investigation in every manifestation? Having set forth these principles, he proposed to class the phenomena of human life in two series of distinct results, demanding, with the ardent insistency of conviction, a special analysis for each. In fact, having observed in almost every type of created thing two separate motions, he assumed, nay, he asserted, their existence in our human nature, and designated this vital antithesis Action and Reaction. "A desire," he said, "is a fact completely accomplished in our will before it is accomplished externally." Hence the sum-total of our Volitions and our Ideas constitutes Action, and the sum-total of our external acts he called Reaction. When I subsequently read the observations made by Bichat on the duality of our external senses, I was really bewildered by my recollections, recognizing the startling coincidences between the views of that celebrated physiologist and those of Louis Lambert. They both died young, and they had with equal steps arrived at the same strange truths. Nature has in every case been pleased to give a twofold purpose to the various apparatus that constitute her creatures; and the twofold action of the human organism, which is now ascertained beyond dispute, proves by a mass of evidence in daily life how true were Lambert's deductions as to Action and Reaction.