Don’t express your ideas too clearly. Most people think little of what they understand, and venerate what they do not. […] Many praise without being able to say why. They venerate anything hidden or mysterious, and they praise it because they hear it praised.

[No allanarse sobrado en el concepto. Los más no estiman lo que entienden, lo que no perciben lo veneran. […] Alaban muchos lo que, preguntados, no saben dar razón. ¿Por qué? Todo lo recóndito veneran por misterio y lo celebran porque oyen celebrarlo.]

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

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 253 (1647) [tr. Maurer (1992)]
    (Source)

(Source (Spanish)). Alternate translations:

Not to be too intelligible. Most part do not esteem what they conceive, but admire what they understand not. [...] Many praise that which they can give no reason for, when it is asked them: because they reverence as a mystery all that is hard to be comprehended, and extoll it, by reason they hear it extolled.
[Flesher ed. (1685)]

Do not Explain overmuch. Most men do not esteem what they understand, and venerate what they do not see. [...] Many praise a thing without being able to tell why, if asked. The reason is that they venerate the unknown as a mystery, and praise it because they hear it praised.
[tr. Jacobs (1892)]

A Bit Vague. For most men have low regard for what they understand, and venerate only what is beyond them. [...] Many praise, but if asked can give no reason: Why? for they revere all that is hidden because mysterious, and they sing its praises, because they hear its praises being sung.
[tr. Fischer (1937)]