Macvicar said that "if extreme vicissitudes of belief on the part of men of science are evidences of uncertainty, it may be affirmed that of all kinds of knowledge none is more uncertain than science;" but slow as mankind is in the progress of discoveries bearing upon unknown laws of nature, men of science are still slower in recognizing truths after they have been discovered and demonstrated. Two centuries elapsed between the discoveries of Pythagoras and their revival by Copernicus. Tycho Brahe opposed the Pythagorean system until his death; Galileo, adopting it and demonstrating it in all its purity, suffered for his support of it at the hands of bigots. And so history now repeats itself. Were it possible to convince scientists en masse of the grandeur of Keely's work, they would protect him from the interruptions and law-suits which have so retarded his progress that now it looks very much as though he would never be permitted to complete his system. The world is full of inventors, but there is but one man able to unfold, to this age and generation, the wonderful mysteries attendant upon vibratory physics, while there are thousands who, when a mastery of the principle has been gained, can invent machinery to apply it to commercial uses. Macvicar asks, "Who that goes so far as to make a question of all, or almost all, the data of common sense can legitimately refrain from making it a question whether the laws of phenomena which men of science discover may not be laws of thinking, merely imposed upon nature as her laws? Nay, who can refrain from admitting with Kant that they can be nothing more?"