However wide the range of experience upon which physical generalizations are based, it can never be so wide as on this score alone to prove the inherent possibility of exceptions; more especially when we consider the confinement of the human race to what is relatively a momentary existence on a whirling particle of dust in a sandstorm. There may indeed be abundant evidence of a certain impetus or tendency enduring from a comparatively distant and indefinite past and making for an equally indefinite future; but there is not, cannot be evidence against the possibility of interference from other laws whose paths, at points unknown and incalculable, intersect those followed by the (to us) ordinary course of events. And in this wholesome agnosticism we are confirmed when we see that while some animals are deprived of certain senses which we possess, and all of them of the gift of reason, others are apparently endowed with senses unknown to us, and are taught by seeming instincts which surpass what reason could effect; whence we may infer that the likelihood of our being _en rapport_ with the greater part of the _possible_ phenomena amidst which we live, or of our possessing all possible senses or the best of those possible, is infinitely small. What a magician a man with eyes would be among a race of sightless men; or a man with ears among a deaf population! How studiously would the scientists explain the effects of sight as produced by subtilty of hearing; and those of hearing as due to abnormal sensitiveness in some other respect!