A wise man sees as much as he ought, not as much as he can.

The saying contrasts mere capacity with ethical judgment. Montaigne’s “wise man” is not the one who pushes perception, inquiry, or scrutiny to the limit, but the one who knows where to stop—guided by prudence, modesty, and a sense of what is fitting. “As much as he can” suggests curiosity or acuity unrestrained; “as much as he ought” introduces a moral measure: wisdom includes self-limitation. Read this way, the line warns against indiscriminate exposure (to others’ faults, to dangerous knowledge, to needless suspicion) and praises discretion—seeing enough to act well, not so much that one becomes cynical, meddlesome, or overwhelmed.