It will give clearness to the question in dispute if I quote here a strong expression of each view in turn. For the physiological or materialist conception of the passion of love,--where love's subliminal element is held to be of the organic type,--set forth in no light or cynical spirit, but with the moral earnestness of a modern Lucretius, I can turn to no better authority than Professor Pierre Janet. The passage which follows is no mere _boutade_ or paradox; it is a kind of culminating expression of the theory which regards the supraliminal man as the normal man, and distrusts all deep disturbance of his accustomed psychical routine. It is commonly said that love is a passion to which man is always liable, and which may surprise him at any moment of his life from 15 to 75. This does not seem to me accurate; and a man is not throughout all his life and at every moment susceptible of falling in love (_de devenir amoureux_). When a man is in good physical and moral health, when he has easy and complete command of all his ideas, he may expose himself to circumstances the most capable of giving rise to a passion, but he will not feel it. His desires will be reasonable and obedient to his will, leading the man only so far as he wishes to go, and disappearing when he wishes to be rid of them. On the other hand, if a man is morally below the mark (_malade au moral_),--if in consequence of physical fatigue or excessive intellectual work, or of violent shocks and prolonged sorrow, he is exhausted, melancholy, distracted, timid, incapable of controlling his ideas,--in a word, _depressed_,--then he will fall in love, or receive the germ of some kind of passion, on the first and most trivial occasion.... The least thing is then enough; the sight of some face, a gesture, a word, which previously would have left us altogether indifferent, strikes us, and becomes the starting point of a long amorous malady. Or more than this, an object which had made no impression on us, at a moment when our mind was healthier and not capable of inoculation, may have left in us some insignificant memory which reappears in a moment of morbid receptivity. That is enough; the germ is sown in a favourable soil; it will develop itself and grow.