The crucial experiment is this.  Offer a bulky and boggy bun to the suspected individual just ten minutes before dinner.  If this is eagerly accepted and devoured, the fact of youth is established.  If the subject of the question changes color and expresses surprise and incredulity, as if you could not possibly be in earnest, the fact of maturity is no less clear.

* * * * *

——­Excuse me,—­I return to my story of the Commons-table.—­Young fellows being always hungry, and tea and dry toast being the meagre fare of the evening meal, it was a trick of some of the Boys to impale a slice of meat upon a fork, at dinner-time, and stick the fork holding it beneath the table, so that they could get it at tea-time.  The dragons that guarded this table of the Hesperides found out the trick at last, and kept a sharp look-out for missing forks;—­they knew where to find one, if it was not in its place.—­Now the odd thing was, that, after waiting so many years to hear of this college trick, I should hear it mentioned a second time within the same twenty-four hours by a college youth of the present generation.  Strange, but true.  And so it has happened to me and to every person, often and often, to be hit in rapid succession by these twinned facts or thoughts, as if they were linked like chain-shot.

I was going to leave the simple reader to wonder over this, taking it as an unexplained marvel.  I think, however, I will turn over a furrow of subsoil in it.  The explanation is, of course, that in a great many thoughts there must be a few coincidences, and these instantly arrest our attention.  Now we shall probably never have the least idea of the enormous number of impressions which pass through our consciousness, until in some future life we see the photographic record of our thoughts and the stereoscopic picture of our actions.  There go more pieces to make up a conscious life or a living body than you think for.  Why, some of you were surprised when a friend of mine told you there were fifty-eight separate pieces in a fiddle.  How many “swimming glands”—­solid, organized, regularly formed, rounded disks, taking an active part in all your vital processes, part and parcel, each one of them, of your corporeal being—­do you suppose are whirled along, like pebbles in a stream, with the blood which warms your frame and colors your cheeks?—­A noted German physiologist spread out a minute drop of blood, under the microscope, in narrow streaks, and counted the globules, and then made a calculation.  The counting by the micrometer took him a week.—­You have, my full-grown friend, of these little couriers in crimson or scarlet livery, running on your vital errands day and night as long as you live, sixty-five billions, five hundred and seventy thousand millions.  Errors excepted.—­Did I hear some gentleman say, “Doubted?”—­I am the Professor.  I sit in my chair with a petard under it that will blow me through the skylight of my lecture-room, if I do not know what I am talking about and whom I am quoting.