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Leonardo's Notes on the Cosmos
(c. 1515)
Leonardo da Vinci

If we consider only his artistic achievements, Leonardo da Vinci (1452-1519), places in the first rank of notable figures from the Italian Renaissance. When we delve into his private notebooks, Leonardo stands out as one of the greatest thinkers in Western history. Not intended for publication and inscribed in a mirror-image hand, his notes include drawings, designs, and speculations covering an extraordinary range of topics and ideas. As a scientist, Leonardo leaned toward mechanics, not surprising from one of the foremost engineers of his time. Various fantastic machines, such as the draft for his "helicopter," capture the imagination of modern students. The notebooks also display his fascination with natural phenomena, such as properties of light, the age of trees, birds in flight, and human anatomy. As we see below, his wide-ranging interests also included the heavens. Untrained in any formal, scholastic sense on the topic, Leonardo challenged accepted notions about the nature of the universe a generation before Polish mathematician Nicolaus Copernicus (1473-1543) upset ancient and medieval norms.

Questions to Consider
  • Whom is Leonardo arguing against in this passage? Why does he seem so irritated?

  • How do these notes represent a synthesis of observation and intuition?

Demonstration that the Earth is a Star

In your discourse you must prove that the earth is a star much like the moon, and the glory of our universe; and then you must treat of the size of various stars according to the authors.

The sun does not move.

The sun has substance, shape, motion, radiance, heat, and generative power: and these qualities all emanate from it without its diminution.

The sun has never seen any shadow.

Praise of the Sun

If you look at the stars without their rays (as may be done by looking at them through a small hole made with the extreme point of a fine needle and placed so as almost to touch the eye), you will see these stars to be so minute that it would seem as though nothing could be smaller; it is in fact the great distance which is the reason of their diminution, for many of them are very many times larger than the star which is the earth with the water. Think, then, what this star of ours would seem like at so great a distance, and then consider how many stars might be set in longitude and latitude between these stars which are scattered throughout this dark expanse. I can never do other than blame many of those ancients who said that the sun was no larger than it appears; among these being Epicurus; and I believe that he reasoned thus from the effects of a light placed in our atmosphere equidistant from the centre; whoever sees it never sees it diminished in size at any distance.

But I wish I had words to serve me to blame those who would fain extol the worship of men above that of the sun; for in the whole universe I do not see a body of greater magnitude and power than this, and its light illumines all the celestial bodies which are distributed throughout the universe. All vital force descends from it since the heat that is in living creatures comes from the soul (vital spark); and there is no other heat nor light in the universe. And certainly those who have chosen to worship men as gods such as Jove, Saturn, Mars, and the like have made a very great error, seeing that even if a man were as large as our earth he would seem like one of the least of the stars which appears but a speck in the universe; and seeing also that men are mortal and subject to decay and corruption in their tombs.

[Thespera] and Marullo and many others praise the sun.


Source: Selections from the Notebooks of Leonardo da Vinci, ed. Irma A. Richter (Oxford, England: Oxford University Press, 1977), 54-55.