Oxford English Dictionary (on line behind paywall)
1.d. Contextually, usually predicative with following infinitive: = a wise thing to do; also with 'a' and plural, a piece of wisdom; a wise action or proceeding. (Opposed to folly n.1 1c) archaic.
1362 W. Langland Piers Plowman A. vii. 201 Here nou..and holde hit for wisdam. [Listen... and accept it as wisdom.]
1831 W. Scott Count Robert vii, in Tales of my Landlord 4th Ser. II. 183 It is wisdom to choose a better protector.
1884 H. H. Jackson Ramona i If she had ever said anything about herself, which she never did—one of her many wisdoms.