tirpate the aged. But as surely as the agnosticism of age is a witness to the weariness of fruitless speculation, so surely the confidence of youth that every movement must of necessity be forward is a proof of insufficiency.
Let the military art instruct us. The raw recruit is satisfied if old Blücher waves his sword, shouting, "Vorwärts!" But the sobered veteran is prepared to see in flank-movements, in retreats, in halts and intrenchments, steps of the campaign as necessary as any charge at double-quick on hostile lines, or a steady march in column into the enemy's country. Let us suppose that in the last twelvemonth not one surprising discovery in any region of the globe has been made; that a hundred previously reported facts have been examined and pronounced untrue; a hundred printed memoirs, widely read and criticised, been proved mistaken or absurd; a hundred long-accepted generic or specific names, fossil or recent, have been expunged from the lists; and that others, like Halysites catenulata or Spirifer disjuncta, have lost their characteristic values; suppose any amount of doubt to have been thrown upon any number of popularly accepted theories, by failures in applying them to practice, like the theory of the anticlinal location of gas-wells; in a word, suppose any amount of smashing in any department of the great crockery-shop of transcendental or applied science—what does it imply but the tendency of all inquiry, observation, investigation, and experiment toward the betterment, which is the only true advancement, of science? As, in the animal kingdom, the peaceful kinds are offset and held in check by analogous carnivores, for fear of over-population, so, in the world of thought, the constructive theorists are perpetually preyed upon by a corresponding class of natural enemies, the destructive critics, which keeps the field open and the air sweet. The destruction of effete knowledge is the perennial birth of that science which can not be destroyed. But, in recognizing the fact, we should remember that there is a science of items and a science of fundamentals, which bear a relation to each other, like that which subsists between the individuals of a species and species per se; and that an indefinite multiplication of individuals may go on without any visible modification of their specific character. The population of Europe has grown in the last century from a hundred and fifty to three hundred and twenty millions of souls; but they are the same Teutons, Celts, and Slavs as ever. On the other hand, the curve of population for France is almost a horizontal straight line; but their national advancement has been phenomenal. What I wish to illustrate is this evident truth, that not by the mere increment of number of facts learned, not by the mere multiplication of discoverers, teachers, and students of those facts, but by the elevation of our aims, by the enlargement of our views, by the refinement of our methods, by the ennoblement of our personalities, and by these alone, can we rightly discover whether or not our asso-
