When you counsel someone, you should appear to be reminding him of something he had forgotten, not of the light he was unable to see.

[Que el aviso haga antes viso de recuerdo de lo que olvidava que de luz de lo que no alcanzó.]

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

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 7 (1647) [tr. Maurer (1992)]
    (Source)

Alternate translation: Princes will allow a man to help them, but not surpass them, and will have any advice tendered them appear like a recollection of something they have forgotten rather than as a guide to something they cannot find. [tr. Jacobs (1892)]