this takes many years to happen, so that one grants it majority indeed soon after the twentieth year, yet has placed full maturity, years of discretion, not before the fortieth year. But while this psychical education, resting upon help from without, is still in process of growth, the inner physical energy of the brain already begins to sink again. This has reached its real calminating point about the thirtieth year, on account of its dependence upon the pressure of blood and the effect of the pulsation upon the brain, and through this again upon the predominance of the arterial over the venous system, and the fresh tenderness of the brain fibre, and also on account of the energy of the genital system. After the thirty-fifth year a slight diminution of the physical energy of the brain becomes noticeable, which, through the gradually approaching predominance of the venous over the arterial system, and also through the increasing firmer and drier consistency of the brain fibre, more and more takes place, and would be much more observable if it were not that, on the other hand, the psychical perfecting, through exercise, experience, increase of knowledge, and acquired skill in the use of it, counteracts it – an antagonism which fortunately lasts to an advanced age, for the brain becomes more and more like a worn-out instrument. But yet the diminution of the original energy of the intellect, resting entirely upon organic conditions, continues, slowly indeed, but unceasingly: the faculty of original conception, the imagination, the plastic power, the memory, become noticeably weaker; and so it goes on step by step downwards into old age, garrulous, without memory, half-unconscious, and ultimately quite childish.
The will, on the contrary, is not affected by all this becoming, this change and vicissitude, but is from beginning to end unalterably the same. Willing does not require to be learned like knowing, but succeeds perfectly at once. The new-born child makes violent movements, rages, and cries; it wills in the most vehement manner,
