of mortals; to great books-the records of life that are truest and most full; to literature-because literature is a transcript of life, and offers us a reading of life that is afforded by nothing else. And the more varied and vital was their experience, the more keen was their enjoyment of the books they read. The more they lived, the more they perceived what voyages of exploration and discovery the masters had made before them, and what treasure had been gathered. Men saw with new vividness literature's contact with life and its profound truth to life; now in Kipling's great knowledge of the British soldier, again in Masefield's or Conrad's studies of the sea. Often a single line or a phrase-as is the case always with the greatest writers disclosed its eternal truth in the flash of a new experience. Let me give an instance.

Captain Norman Hall in one of his charming papers on "High Adventure," contributed to the Atlantic Monthly, tells of his making the two cross-country triangular flights of 200 kilometers each, which were part of the test every pilote had to pass before he became a military aviator. He and his friend Drew started off, one close behind the other, and after flying over an old cathedral town and for the first time seeing villages and chateaux, stretches of forest and miles of open country from a height of 5,000 feet, they met at the rendezvous. It was a new experience, and both were full of fresh sensations. Drew was the first to break forth in exclamation. "It was lonely! Yes, by Jove! that was it. 'Lonely as a cloud.' Happy choice of simile. Wordsworth had imagination. He must have known."

Thus have men tested the truth of great poetry, and found in literature a running comment on life. It took a hundred years and the power to fly, before we got the full measure of the imaginative truth of that line. Wordsworth "must have known!" Yes, they all seem to have known-the great writers -and it takes us years of living, of living often of the most intense kind, to gather, through experience, what they knew in a glance of the eye.

And then the element of beauty in literature. The need of

beauty is with most of us an ever-present need, one that we satisfy in one way or another-through pictures, sculpture music, architecture, or simply by taking a walk in the country or raising a few flowers in the back yard. But during the war, such enjoyments were greatly limited, and at the front, life was almost devoid of beauty. What little there was, was as a fountain in a great desert. A soldier wrote from the trenches, "I saw a few wind-flowers the other day, and a vast meadow full of kingcups, and that was enough to make me happy for weeks." Such a remark, I think, helps us to understand why so many turned to the poets, to Shakespeare, Wordsworth, Shelley, and Keats. In them they found, among other things, the beauty of perfect art. On the day after a great advance a doughboy wrote, "On such a day as this, one wishes to read well-expressed words which deal with eternal things." The phrase takes us back to Keats's line about beauty and truth, and we perceive that many of the fighters in this war have found in literature a kind of pleasure not greatly different from that felt by poets exalted on high.

To students of literature such reflections must be gratifying. But perhaps the most interesting aspect of all this war-time use of books is that it has demonstrated, as nothing ever before demonstrated, the truth that literature is a vital power in man's life. The relatively few who have really loved great writings have known this all along. But those who see in literature only an idle pastime or an escape from ennui have been many. These have looked upon it as a mere luxury, an ornament for a wealthy society, a drawing-room sort of thing that men and women have time for only when they are comfortable in mind, body and estate; very good perhaps in time of peace and prosperity, but a mere vanity to a nation going through a great crisis or suffering the agonies of war. They have thought of writers as dreamers and visionaries, and of their works as being fit for him whom the low-brow calls the high-brow, but not for hard-headed men who have work to do in the world. But now, it seems to me, the war has made it clear, even to the most insufferably practical of practical men, that literature is

not a thing above and apart, but a power that touches life very nearly; and that it is for the red-blooded man of action as well as the student, for the man of the world as well as the recluse. At least, we may say truly that in these four years it has served well some of the greatest heroes that time has seen, and has been a solace and a joy to those who have now finished successfully the greatest task that man was ever called on to perform.

THE MICROSCOPE

BY CLARENCE E. MCCLUNG

Professor of Zoology and Director of the Zoological Laboratory

There are many ways in which the microscope may be regarded. There is mystery and romance in its invention—the high light of intellectual renaissance and the black shadow of the inquisition mark its birth. While the modern telescope of massive proportion is turned to the sky in study of far distant worlds, and while the more modestly proportioned miscroscope searches out the intimate nature of our own globe, in the beginning these two instruments were one. It is most interesting to note that both the Dutch and Keplerian telescopes were early made use of for the magnification of near objects and that, in the hands of such masters as Galileo, they almost simultaneously played their double role.

The enquiring mind with a new tool at once sought scope for its action, and so we may not with certainty say whether Galileo or Drebbel or Jansen invented the microscope by utilizing a telescope for the observation of nearby objects. Since, however, there were the two kinds of telescopes in the hands of these men, it is very probable that each came independently to the application of an optical instrument to the same purpose. If so, it would appear that Zacharias Jansen in 1590, or Galileo in 1610, first saw an enlarged image of a near object by the use of a Dutch telescope, while Drebbel, in 1621, witnessed the same effect through a Keplerian telescope.

Here, as so often is the case with human inventions or discoveries, a common impulse led several men nearly at the same time, to the same end. Given convex lenses, there must eventually come the discovery of their magnifying power, and, with that, their application to the observation of both near and remote objects. Yet it is most surprising that for centuries men should, as they must, have noted and recorded the enlarged

appearance of objects seen through bowls of water and have failed to discover that it was the presence of curved surfaces, and not the contained water, which produced the effect. Once lenses were invented the production of microscope and telescope inevitably followed. And how nearly simultaneously these instruments came to the thought of several men after all the centuries of waiting! Glass and metal and the obvious action of curved surfaces upon light rays were the daily contact and experience of sages, philosophers and plain men through many, many years of intellectual activity-and yet no synthesis of these into an instrument of enlarged vision followed. The stars passed on their courses, some seen, others invisible; the mysteries of growth and development in the bodies of living things unfolded in ever recurring cycles without note-all because no one thought of the simple size relation revealed by the juxtaposition of the curved surface of the fish bowl and the tiled figure beneath it.

Almost at once an end came to this ignorance. A solid, transparent body with convex surfaces displayed to some one the same phenomenon as the fish bowl-it could not be the water therefore, but must be the surface effect upon the lightand the idea of a lens was born. Doubtless the more exact image in a polished mirror, as compared with an irregular reflecting surface, suggested the grinding and polishing process as a means of improving the action of the glass body transmitting light. But when lenses were devised and by whom we have no knowledge. A clear understanding of the action of transparent media of different density upon transmitted light was expressed by Ptolemaeus who wrote upon the subject early in the second century of the present era, but there is no indication that he recognized the power of curved surfaces to change the image of objects. Not until the time of Roger Bacon in the thirteenth century do we find mention of this property of lenses. To most thoughtful men in all preceding time the idea of enlarged images was in some way involved with the action of water. As Seneca says, "anything, in fact, that is seen through moisture appears far larger than it really is." Bacon's Opus Majus contains full