of the mathematics of their time. The differential gave them the same spasms as the negation of the negation gives Herr Duehring and it played a role in it as we shall see. They admitted it at last, at least as many as did not die first, not because they were convinced but because it always worked out right. Herr Duehring, is, as he says, just in his forties, and if he attains old age, as we hope he will, he may also experience the same.
But what is this dreadful negation of the negation which makes life so bitter to Herr Duehring and which is to him what the unpardonable sin, the sin against the Holy Ghost, is to Christianity? It is a very simple process, and one, moreover, which fulfils itself every day, which any child can understand when it is, deprived of mystery, under which the old idealistic philosophy found a refuge, and beneath which it will pay unprotected metaphysicians to take refuge from the stroke of Herr Duehring. Let us take a grain of barley. Millions of such grains of barley will be ground, cooked and brewed and then consumed. But let such a grain of barley fall on suitable soil under normal conditions; a complete individual change at once takes place in it under the influence of heat and moisture, it germinates. The grain, as such disappears, is negated, in its place arises the plant, the negation of the grain. But what is the normal course of life of this plant? It grows, blossoms, bears fruit and finally produces other grains of barley and as soon as these are ripe the stalk dies, and becomes negated in its turn. As the result of this negation of the negation, we have the original grains of barley again, not singly, however, but ten, twenty or thirty fold. Forms of grain change very slowly and so the grain of barley remains practically the same as a hundred years ago. But let us take a cultivated ornamental plant, like the dahlia or
