The principle upon which science rests is that its laws are capable of verification, and that they are verified when and if they are confirmed by experience. The final appeal of science is to the evidence of consciousness, the only evidence of what is that we possess: the only evidence of the truth and accuracy with which an eclipse has been calculated is the evidence of our senses that the eclipse does take place and is visible in the place and at the time predicted. If a hypothesis predicts results which as a matter of observation do not take place, the hypothesis is judged so far inaccurate or inadequate: what is over-rides our preconceived opinions, even if they be the hypotheses of science, as to what ought to be or will be. It is the ever-open appeal to the final court of fact, of what is, that condemns false assumptions, guarantees the truth of science, and safeguards the freedom of scientific inquiry. To allow any group of men, however eminent, or any body of science, however sound, to deprive us of this right of appeal and bid us disbelieve in the evidence of our own senses, if it contradicts their theories, would be to submit to the tyranny of dogmatism, and to be faithless to the cause of truth. Fortunately, though the unconscious and therefore ill-considered metaphysics of some men of science have tended in the direction of scientific dogmatism, the practice of science has been in the opposite direction. In practice science has owed much of her progress to the study of "residual phenomena." Phenomena which the laws of science for the moment could not account for have not been denounced as illusions, or ruled out of court as non-existent or beneath the notice of science: they have been accepted as facts, as part of the totality of things which it is the ambition of science to account for; and, accepted as such, they have led, it may be, to the discovery of a new planet or a new element, but always to the discovery of fresh truths, which never would have enriched the page of science had science refused to take cognisance of facts the laws of which it had not at the time discovered.