Set thine eyes - literally, as in the margin, i. e., "gaze eagerly upon;" and then we get an emphatic parallelism with the words that follow, "they fly away as an eagle toward heaven;" "certainly make themselves wings."

Wilt thou set thine eyes upon that which is not?.... The Vulgate Latin version is,
"do not lift up thine eyes to riches which thou canst not have;''
riches no doubt are intended, and which may be said to be "not"; they are not the true riches, have only the shadow and appearance of riches; they are not lasting and durable; in a little time they will not be; they are perishing things, they have no substance or solidity in them; they are not satisfying; they do not make them happy; they are rather nonentities than realities; and therefore the eyes of the mind and the affections of the heart should not be set on them: it may be rendered, "wilt thou cause thine eyes to fly upon that which is not?" (w) denoting the intenseness of the mind, and the eagerness of the affections, and with what rapidity and force they move towards them. The Targum is,
"if thou fixest thine eyes on him, he shall not appear to thee;''
meaning the rich man: and so the Septuagint, Syriac, and Arabic versions. Ben Melech makes mention of other senses very different; according to R. Judah, the word signifies darkness, "wilt thou make thine eyes dark?" two according to others, signifies light, "wilt thou make thine eyes to shine?" and, according to Jarchi, "wilt thou double?", or shut thine eyes?
for riches certainly make themselves wings; or, "it in making makes itself wings" (x); even that which is not, on which men cause their eyes to fly; no sooner are their eyes upon that, but that flies away from them like a bird with wings; see Hosea 9:11. Either men are taken from that, or that from them, and sometimes very swiftly and suddenly;
they fly away as an eagle towards heaven; the eagle flies very swiftly, none more swiftly; it flies towards heaven, out of sight, and out of reach, and out of call; so riches flee away to God, the original giver of them, from whence they came, and who is the sole disposer of them; they own him as the proprietor and distributor of them; and they flee to heaven as it were for fresh orders where they should be, and into whose hands they should come next; they flee away, so as not to be seen any more, and be recovered by those who have formerly enjoyed them.
(w) "numquid involare facies", Michaelis; "ut involent", Junius & Tremellius; "ut volent", Piscator; "ad sineves volare", Cocceius. (x) "quis faciendo faciet", Montanus, Baynus.

Wilt . . . eyes--As the eyes fly after or seek riches, they are not, that is, either become transitory or unsatisfying; fully expressed by their flying away.

Set thine eyes - Look upon it with earnestness and desire. Is not - Which has no solid and settled being. Eagle - Swiftly, strongly, and irrecoverably.