Let us add that thought, too, propagates itself throughout mankind, in like manner with the germ plasm.
Every thought, once expressed, leads in the human community a life independent of its creator; undergoes development in other minds; and has, like the germ plasm, an immortal life. So that, in humanity, there is neither true birth nor true death, whether material or spiritual. Empedocles, of old, realised this, for he said:
“Yet another truth will I tell unto thee. Not a mortal thing is truly born, and death the destroyer is not the end. There is nought but intermixture and exchange of what is intermixed. But among men it is customary to term this ‘birth.’”
Humanity, therefore, materially and spiritually, is a single organism; all its parts are intimately connected and share in a common development.
Upon these ideas there must now be grafted the concept of mutation and the observations of Hugo de Vries.—If this living substance which is common to all humanity should, at any time and owing to any influence, have acquired the capacity for changing[1] after a certain lapse of time, for instance a thousand years, then all those beings which have in them a share of this substance may suddenly undergo identical changes. It is well known that Hugo de Vries has observed such sudden variations in plants.[2] After centuries of stability in the characteristics of a species, quite suddenly, in a great number of individuals belonging to this species, there will one year occur a modification, the leaves becoming longer, or shorter, etc. Thenceforward this modification will be propagated as a constant feature, so that, by the following year, a new species will have come into existence.—The same thing happens among human beings, especially in the human brain; for, as far as man is concerned, the most striking instances of variation are
