“Sorrow is hard to bear, and doubt is slow to clear. 
    Each sufferer says his say, his scheme of the weal and woe: 
  But God has a few of us whom he whispers in the ear;
    The rest may reason and welcome:  ’tis we musicians know."[A]

[Footnote A:  Abt Vogler.]

And side by side with the poetry that grasps the truth in immediate intuition, there is also the uniting activity of philosophy, which, catching up its hints, carries “back our scattered knowledge of the facts and laws of nature to the principle upon which they rest; and, on the other hand, develops that principle so as to fill all the details of knowledge with a significance which they cannot have in themselves, but only as seen sub specie aeternitatis."[B]

[Footnote B:  The Problem of Philosophy at the Present Time, by Professor Caird.]

So far we have spoken of the function of philosophy in the interpretation of the phenomena of the outer world.  It bears witness to the unity of knowledge, and strives by the constructive criticism of the categories of science to render that unity explicit.  Its function is, no doubt, valid and important, for it is evident that man cannot rest content with fragmentary knowledge.  But still, it might be objected that it is premature at present to endeavour to formulate that unity.  Physics, chemistry, biology, and the other sciences, while they necessarily presuppose the unity of knowledge, and attempt in their own way and in their own sphere to discover it, are making very satisfactory headway without raising any of the desperate questions of metaphysics as to its ultimate nature.  For them it is not likely to matter for a long time to come whether Optimism or Pessimism, Materialism or Idealism, or none of them, be true.  In any case the principles they establish are valid.  Physical relations always remain true; “ginger will be hot i’ the mouth, and there will be more cakes and ale.”  It is only when the sciences break down beneath the weight of knowledge and prove themselves inadequate, that it becomes necessary or advantageous to seek for more comprehensive principles.  At present is it not better to persevere in the way of science, than to be seduced from it by the desire to solve ultimate problems, which, however reasonable and pressing, seem to be beyond our power to answer?

Such reasonings are not convincing; still, so far as natural science is concerned, they seem to indicate that there might be no great harm in ignoring, for a time, its dependence on the wider aspects of human thought.  There is no department of nature so limited, but that it may more than satisfy the largest ambition of the individual for knowledge.  But this attitude of indifference to ultimate questions is liable at any moment to be disturbed.