Skepticism is the chastity of the intellect, and it is shameful to surrender it too soon or to the first comer: there is nobility in preserving it coolly and proudly through long youth, until at last, in the ripeness of instinct and discretion, it can be safely exchanged for fidelity and happiness.

Santayana likens skepticism to “chastity” to stress its protective, self-respecting function: the mind should not give its assent cheaply. For him, doubt is not an end in itself but a discipline that guards against credulity, fashion, and premature dogma. The image of “long youth” suggests an intellectual maturation in which one tests ideas, motives, and authorities before committing. Only when judgment has ripened—through experience, instinct, and discretion—can skepticism be “exchanged” for a stable loyalty (“fidelity”) that is not naïve but earned. The quote thus defends a measured path between gullibility and cynical disbelief: rigorous reserve first, then considered commitment.