“That which is produced with intention has passed over from non-existence to existence.”
Source: Guide for the Perplexed (c. 1190), Part III, Ch.13
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Maimónides 180
rabbi, physician, philosopher 1138–1204Related quotes

Alternate translation: Not one of our mortal gauges is suitable for evaluating non-existence, for making judgments about that which is not a person.
Ни одна наша смертная мерка не годится для суждения о небытии, о том, что не есть человек.
Note-Book of Anton Chekhov (1921)

“In principio it is impossible to prove from experiments that something is non-existent.”
The Magnetic Current http://adsabs.harvard.edu/abs/1941Sci....94..232E, Science, Volume 94, Issue 2436, pp. 232-233 (September, 1941)

Principles of Mathematics (1903), p. 450
1900s

(1964) Fada’ih al-Batiniyya. Edited by Abdurahman Badawi. Kuwait: Muasassa Dar al-Kutub al-Thiqafa, p. 82.

Source: The Sayings and Teachings of the Great Mystics of Islam (2002), p.112