[6] This term is now applied almost exclusively to _physical science_, or that whose province is the observation of phenomena and inferences directly deducible from them. To avoid confusion, this sense of the word "Science" will be here adopted: it is nevertheless objectionable inasmuch as it implies that--as Professor Huxley following Hume would have it--sound knowledge is restricted, outside the field of mathematics, to "experimental reasoning concerning matter of fact and existence." But although all premisses or data of inference come to us first through the gates of sense, there is much, beyond the limits within which sensible experience is confined, to a knowledge of which inference can lead us, and of which we become certain before experience can verify what we have thus learnt. Thus a chipped flint or a fragment of pottery is universally recognized as evidencing the work of man: a single page of Virgil would suffice--apart from all other information--to prove its author to have been both a poet and a scholar: the shipwrecked mariner cast on an unknown shore argued soundly from the sight of a gibbet that he had reached a civilized land ruled by law. But more than this, Science herself proceeds on this principle to the recognition not only of forces, the character of which is known by previous experience, but of others concerning which she knows nothing at all, except through the very effects from which she argues. Thus, as all bodies left free are found to draw towards one another in a certain mode, it is concluded with absolute confidence that there is a force making them do so, although this is in itself utterly imperceptible, and is known only by the way in which bodies behave under what must be its influence. Yet, who questions the existence of Gravitation? In like manner, the phenomena of light force us to admit the existence of the Ether, as the medium through which its waves are transmitted. Yet, we are compelled to attribute to this medium qualities apparently so incompatible that, as the late Lord Salisbury said, Ether remains, "a half discovered entity." But little as we can realize its nature, we have no doubt that such a medium exists. [7] "Value of the Natural History Sciences" (_Lay Sermons_), p. 75. [8] Italics his. [9] _Confession of Faith of a Man of Science_, English translation, 1903, Preface, p. vii. [10] _Riddle of the Universe_, Cheap English Edition, p. 2. [11] _ibid._, p. 85. [12] And also, it should be added, travelling bodily through space with a movement of "translation." [13] _Ibid._ [14] _Ibid._, p. 2. [15] The 15th Chapter of Haeckel's _Natural History of Creation_ is devoted to this point. [16] _Confession of Faith of a Man of Science_, p. 32. [17] _Riddle of the Universe_, p. 5. [18] _Ibid._, p. 78. [19] _Ibid._, p. 86. [20] _Ibid._, 134. [21] _An Easy Outline of Evolution_, by Dennis Hird, M.A., Principal of Ruskin Hall, Oxford, p. 230.