Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
THE Hebrew ‘ayin is a homonym, signifying "fountain"; e.g., "By a fountain (‘en) of water" (Gen. xvi. 7). It next denotes "eye"; comp. (‘ayin) "Eye for eye" (Exod. xxi. 24). Another meaning of the word is "providence," as it is said concerning Jeremiah, "Take him and direct thine attention (eneka) to him" (Jer. xxxix. 12). In this figurative sense it is to be understood when used in reference to God; e.g., "And my providence and my pleasure shall be there perpetually" (1 Kings ix. 3), as we have already explained (page 140); "The eyes (‘ene), i.e., the Providence of the Lord thy God, are always upon it" (Deut. xi. 12); "They are the eyes (‘ene) of the Lord, which run to and fro through the whole earth" (Zech. iv. 10), i.e., His providence is extended over everything that is on earth, as will be explained in the chapters in which we shall treat of Providence. When, however, the word "eye" is connected with the verb "to see," (raah or ḥazah) as in "Open thine eyes, and see" (1 Kings xix. 16); "His eyes behold" (Ps. xi. 4), the phrase denotes perception of the mind, not that of the senses: for every sensation is a passive state, as is well known to you, and God is active, never passive, as will be explained by me.