In the transcendental or ultra-mundane or supersensual region there is the further difficulty to be encountered, that we are not acquainted with anything like all the 'boundary conditions,' so to speak; we only know our little bit of the boundary, and we may err egregiously in inferring or attempting to infer the remainder. We may even make a mistake as to the form of function adapted to the case. Nevertheless there is no better clue, and the human mind is impelled to do the best it can with the confessedly imperfect data which it finds at its disposal. The result, therefore, in this region, is no system of definite and certain truth, as in Physics, but is either suspense of judgment altogether, or else a tentative scheme or working hypothesis, to be held undogmatically, in an attitude of constant receptiveness for further light, and in full readiness for modification in the direction of the truth. So far concerning the ascertainment of truth alone, in intangible regions of inquiry. The further hypothesis that such truth when found will be most satisfactory, or in other words higher and better than any alternative plan,—the conviction that faith in the exceeding grandeur of reality shall not be confounded,—requires further justification; and its grounds are not so easy to formulate. Perhaps the feeling is merely human and instinctive; but it is existent and customary I believe among physicists, possibly among men of Science in general, though I cannot speak for all; and it must be based upon familiarity with a mass of experience in which, after long groping and guess-work, the truth has ultimately been discovered, and been recognised as 'very good.' It is illustrated, for instance, by the words in which Tyndall closes the first edition of his book on Sound, wherein, after explaining Helmholtz's brilliant theory of Corti's organ and the musical mechanism of the ear,—a theory which, amid the difficulties of actual observation, was necessarily at first saturated with hypothesis, and is not even yet fully verified,—he says:— "Within the ears of men, and without their knowledge or contrivance, this lute of 3000 strings has existed for ages, accepting the music of the outer world, and rendering it fit for reception by the brain.... I do not ask you to consider these views as established, but only as probable. They present the phenomena in a connected and intelligible form; and should they be doomed to displacement by a more correct or comprehensive theory, it will assuredly be found that the wonder is not diminished by the substitution of the truth." CHAPTER VI MIND AND MATTER