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First of all define the eye; then show how the twinkling of a star exists really in the eye, and why one star should twinkle more than another, and how the rays of the stars are born in the eye. Say, that if the twinkling of the stars were, as it appears to be, really in the stars, that this twinkling appears to extend in proportion to the body of the star. The star, therefore, being larger than the earth, this motion made in an instant of time would in its velocity double the size of the star. Then prove that the surface of the atmosphere, contiguous to fire and the surface of fire, where it ends, is the point in which the rays of the sun penetrate and bear the image of the celestial bodies which are large when they rise and set, and small when they are on the meridian.

First of all define the eye; then show how the twinkling of a star exists really in the eye, and why one star should twinkle more than another, and how the rays of the stars are born in the eye. Say, that if the twinkling of the stars were, as it appears to be, really in the stars, that this twinkling appears to extend in proportion to the body of the star. The star, therefore, being larger than the earth, this motion made in an instant of time would in its velocity double the size of the star. Then prove that the surface of the atmosphere, contiguous to fire and the surface of fire, where it ends, is the point in which the rays of the sun penetrate and bear the image of the celestial bodies which are large when they rise and set, and small when they are on the meridian.

Approximate author period: c. 1486 AD · medieval

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Attribution & collection notes
Author or tradition
Leonardo da Vinci
Attribution: attributed
Country attributed
Not established
A country attribution does not establish the earliest origin.
Historical period
Approximate author period: c. 1486 AD · medieval
author lifetime midpoint (1452–1519); not quotation composition date
An author lifetime, approximate period or collection date is not necessarily the date when these words were first written or spoken.
Recorded source
Thoughts on Art and Life (1906 English edition) (1906 AD)

Thoughts on Science, complete printed unit 48; Maurice Baring translation; Boston: The Merrymount Press,1906

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Leonardo da Vinci: Drawn portrait

Represented by the complete source-numbered selections in Thoughts on Art and Life, Maurice Baring’s1906English translation, edited by Lewis Einstein. The catalogue records1452–1519; the historical collection is a selection from notebooks, not a continuous book composed by Leonardo or independent authentication of every attributed passage.

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