 Of all the objects in the heavens, none has been more closely nor more consistently observed than the moon. Now that man has actually walked upon her surface, one might suppose that all that can be known about her is known, and it comes as something of a surprise to learn that over all the weighty volumes of astronomical discussion hovers a haunting and tantalizing question. Scattered over the surface of the moon in great profusion are craters. Not unlike the craters produced by volcanoes on the Earth. It was one of these craters which attracted the interest of Sir William Herschel, greatest astronomer of the 18th century. On a certain night in the year 1783, he stood at his accustomed place by the window to study, his telescope to his eye. Beside him was his sister, Carolyn Herschel. Good Lord, I must be dreaming. Here, Carolyn, take the telescope. Where shall I look? It's one of the moon's craters. It's in the lowmost area just below the Mare Ibrahim. The light, they're all in a row, and they're moving, just like the flare of torch lights in a procession. From then on, night after night, Sir William and his sister watched the moon, the infinitesimal pinpoints of illumination that marched mysteriously across the floor of the crater. In that same year and again four years later, in 1787, the great astronomer wrote articles which carried but one implication, that the phenomenon which he had been observing was an evidence of life, that there were perhaps living, moving organisms on the surface of the moon. Sixty years afterward, another eminent scientist named Rankin testified that he too had seen lights in the same crater during an eclipse. And in the decade that followed, four other observers made similar reports. Meanwhile, however, the science of astronomy had reached adulthood. The instrument it employed had gained power and precision. The men who employed them were no longer inclined toward naive and idle speculation. It must be remembered that Sir William Herschel used a telescope of just six feet focal length, which he made with his own hands. Naturally, such an instrument could not produce results in which we can place any reliance whatsoever. The moon, as we now know, is totally devoid of both air and water, and so, of course, it is nonsense to speak of life on its surface. And this was the consensus of opinion for half a century thereafter. And then the great American astronomer, William Henry Pickering, who had devoted a lifetime to planetary photography, who had traveled round the world for the sole purpose of comparing the moon's craters with the craters of the Earth, issued a statement in 1937, just a year before he died. I have observed closely the crater, which so interested my very great predecessor, Sir William Herschel. My conclusions are not entirely at variance with his. There are reasons for believing that there is life on the moon. And so today the problem remains unresolved. And meanwhile, the moon herself rides serenely through the skies, keeping her own confidence and withholding so far her secret. A secret that may well prove incredible but true.