At twenty the will rules; at thirty the intellect; at forty the judgment.

[A los veinte años reina la voluntad, a los treinta el ingenio, a los cuarenta el juicio.]

Baltasar Gracián y Morales (1601-1658) Spanish Jesuit priest, writer, philosopher

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 298 (1647) [tr. Jacobs (1892)]
    (Source)

(Source (Spanish)). Alternate translations:

At twenty years of age the Will reigns; at thirty the Wit; at fourty, the Judgment.
[Flesher ed. (1685)]

At twenty years desire rules us, at thirty, expediency, at forty, judgment.
[tr. Fischer (1937)]

When one is twenty, the will reigns; a thirty, the intelligence; at forty, judgment.
[tr. Maurer (1992)]

See also:

At 20 years of age the Will reigns; at 30 the Wit; at 40 the Judgment.
[Benjamin Franklin, Poor Richard's Almanack (1741)