The observer, if he be a cautious man, begins to see if he can disprove his own conclusion; moreover, being human, he is probably somewhat awed, if not appalled, by his own conclusion.  Hundreds of thousands of years spent in making that little glen!  Common sense would say that the longer it took to make, the less wonder there was in its being made at last:  but the instinctive human feeling is the opposite.  There is in men, and there remains in them, even after they are civilised, and all other forms of the dread of Nature have died out in them, a dread of size, of vast space, of vast time; that latter, mind, being always imagined as space, as we confess when we speak instinctively of a space of time.  They will not understand that size is merely a relative, not an absolute term; that if we were a thousand times larger than we are, the universe would be a thousand times smaller than it is; that if we could think a thousand times faster than we do, time would be a thousand times longer than it is; that there is One in whom we live, and move, and have our being, to whom one day is as a thousand years, and a thousand years as one day.  I believe this dread of size to be merely, like all other superstitions, a result of bodily fear; a development of the instinct which makes a little dog run away from a big dog.  Be that as it may, every observer has it; and so the man’s conclusion seems to him strange, doubtful:  he will reconsider it.

Moreover, if he be an experienced man, he is well aware that first guesses, first hypotheses, are not always the right ones; and if he be a modest man, he will consider the fact that many thousands of thoughtful men in all ages, and many thousands still, would say, that the glen can only be a few thousand, or possibly a few hundred, years old.  And he will feel bound to consider their opinion; as far as it is, like his own, drawn from facts, but no further.

So he casts about for all other methods by which the glen may have been produced, to see if any one of them will account for it in a shorter time.

1.  Was it made by an earthquake?  No; for the strata on both sides are identical, at the same level, and in the same plane.

2.  Or by a mighty current?  If so, the flood must have run in at the upper end, before it ran out at the lower.  But nothing has run in at the upper end.  All round above are the undisturbed gravel beds of the horizontal moor, without channel or depression.

3.  Or by water draining off a vast flat as it was upheaved out of the sea?  That is a likely guess.  The valley at its upper end spreads out like the fingers of a hand, as the gullies in tide-muds do.

But that hypothesis will not stand.  There is no vast unbroken flat behind the glen.  Right and left of it are other similar glens, parted from it by long narrow ridges:  these also must be explained on the same hypothesis; but they cannot.  For there could not have been surface-drainage to make them all, or a tenth of them.  There are no other possible hypotheses; and so he must fall back on the original theory—­the rain, the springs, the brook; they have done it all, even as they are doing it this day.