rolling stone

Cf. [Erasmus Adages iii. iv.] λίθος κυλίνδόμɛνος ṯὸ ϕῦκος οὐ ροίɛῖ, a rolling stone does not gather sea-weed; musco lapis volutus haud obducitur, a rolling stone is not covered with moss.

Selden Moseth [becomes mossy] the Marbelston that men ofte treden.
[1362 Langland Piers Plowman A. x. 101]

The rollyng stone neuer gatherth mosse.
[1546 J. Heywood Dialogue of Proverbs i. xi. D2]

A rowling stone gathers no mosse, and a running hed wil neuer thriue.
[1579 S. Gosson Ephemerides of Phialo 5^V]

A Rolling Stone is ever bare of Moss.
[1710 A. Philips Pastorals ii. 8]

Your popular rumour, unlike the rolling stone of the proverb, is one which gathers a deal of moss in its wanderings up and down.
[1841 Dickens Old Curiosity Shop II. xlviii.]

A roadside notice‥said in one long line: Loose stones travel slowly. Well, I dare say they do: rolling stones, we know, gather no moss.
[1979 Listener 5 July 16]

Related to: constancy and inconstancy; human nature

Bibliography of major proverb collections and works cited from modern editions is available here.

A person who moves about a great deal and never settles down, as in Kate's lived in ten cities in as many years--she's a real rolling stone. This expression is a shortening of the proverb a rolling stone gathers no moss, first recorded in 1523, which indicates that one who never settles anywhere will not do well. After some 300 years of this interpretation, in the mid-1800s the value of gathering moss (and staying put) began to be questioned, and in current usage the term is most often used without any particular value judgment.