7.  And God said, Let there be light. Gen. i. 3.  The first word of God created the nature of light; it made darkness vanish, dispelled gloom, illuminated the world, and gave to all beings at the same time a sweet and gracious aspect.  The heavens, until then enveloped in darkness, appeared with that beauty which they still present to our eyes.  The air was lighted up, or rather made the light circulate mixed with its substance, and, distributing its splendour rapidly in every direction, so dispersed itself to its extreme limits.  Up it sprang to the very æther and heaven.  In an instant it lighted up the whole extent of the world, the North and the South, the East and the West.  For the æther also is such a subtle substance and so transparent that it needs not the space of a moment for light to pass through it.  Just as it carries our sight instantaneously to the object of vision, Light is said to travel straight at the rate of about 195,000 English miles a second; a velocity estimated by observations on the eclipses of Jupiter’s satellites.  The modern undulatory theory of light, of which Huyghens († 1695) is generally regarded as the author, describes light as propagated by the vibrations of the imponderable matter termed Ether or Æther. so without the least interval, with a rapidity that thought cannot conceive, it receives these rays of light in its uttermost limits.  With light the æther becomes more pleasing and the waters more limpid.  These last, not content with receiving its splendour, return it by the reflection of light and in all directions send forth quivering flashes.  The divine word gives every object a more cheerful and a more attractive appearance, just as when men in deep sea pour in oil they make the place about them clear.  So, with a single word and in one instant, the Creator of all things gave the boon of light to the world. The simile seems hardly worthy of the topic.  The practice is referred to by Plutarch, Symp. Quæst. i. 9, and by Pliny, Hist. Nat. ii. 106.  “Omne oleo tranquillari; et ob id urinantes ore spargere, quoniam mitiget naturam asperam lucemque deportet.”  “gerere” says the Delph. note, “tum credas oleum vicem conspiciliorum.