Don’t write so you can be understood. Write so that you cannot be misunderstood.

Quintilian (39-90) Roman orator [Marcus Fabius Quintilianus]
De Institutione Oratoria, Book 8, ch. 2, l. 24

Alt. trans.: "We should not write so that it is possible for [the reader] to understand us, but so that it is impossible for him to misunderstand us."

Also attributed to Epictetus, Francis Bacon, Robert Louis Stevenson, Ralph Waldo Emerson, and William Taft.