“The moon,” says Dr. O. Gregory, “is a dark, or opake body, shining principally with the light she receives from the sun. If she shone by a light of her own, we should feel a sensible warmth from her rays; but it is a light reflected from the sun with which she shines, and is so exceedingly weak and languid, that the greatest burning glass will not collect enough to make any sensible degree of heat. This has been accounted for, and those who have gone through the computation assert that the light of the full moon is ninety thousand times less than day-light.” The ancients early discovered, that the moon had no light of its own, but shone with that which it reflected from the sun. This, after Thales, was the sentiment of Anaxagoras and Empedocles, who thence accounted not only for the mildness of its splendor, but the imperceptibility of its heat, which our experiments confirm. In the Hebrew language the moon is called ירה _Yarah_, or, more strictly speaking, says Parkhurst, the _lunar light_, or _flux of light, reflected from the moon’s body_, or _orb_. That this is the true sense of the word is evident from several passages of Scripture, one of which is, “For the precious (produce) נרש ירחים _put forth by_--what? Not the _orbs_ of the moon surely (for the orb is but _one_), but _by the fluxes_ or _streams of light_ reflected from it, which are not only _several_ but _various_, according to the moon’s different phases and aspects in regard to the sun and the earth. And this may lead us to the radical idea of the word ירח; for as יחר and אחר,‎ יחד and אתד &c., are very nearly related to each other respectively, so likewise I conjecture that ירח is to ארה, in sense as well as in sound, and consequently that it signifies _to go in a track_ or _in a constant customary road or way_; and this affords us a good descriptive name of the _lunar light_; for, _Behold_, says _Bildad_ in Job, chap. xxv, 5, _even to the_ ירח or lunar light ולא יאהיל _and he_ (God) _hath not pitched a tent_ (for it); as he has for the שמש or _solar light_. No! The _lunar_ stream has _fixed station_ from whence it issues, but together with the orb which reflects it, and which like a human _traveller_ moves now a quicker, now a slower pace, is continually _performing its appointed journey_, and _proceeding in a constant_, though regularly irregular _track_.”