[proverb, saying, maxim], Middle English saue, at first in a general sense, "what is said, talk, words," from Old English sagu "saying, discourse, speech, study, tradition, tale," from Proto-Germanic *saga-, *sagon- (source also of Middle Low German, Middle Dutch sage, zage, German Sage "legend, fable, saga, myth, tradition," Old Norse saga "story, tale, saga"), from PIE root *sek(w)- "to say, utter" (see say (v.)).
The surviving specific sense of "proverb, saying, maxim" is by late 13c. "[A] contemptuous term for an expression that is more common than wise" [Century Dictionary].
"full of instructive sayings," 1784, from French gnomique (18c.) and directly from Late Latin gnomicus "concerned with maxims, didactic," from Greek gnōmikos, from gnōmē "a means of knowing, a mark, token; the mind (as the organ of knowing), thought, judgment, intelligence; (one's) mind, will, purpose; a judgment, opinion; maxim, the opinion of wise men," from root of gignōskein "to come to know," from PIE root *gno- "to know." Gnomical is attested from 1610s.
"commandment or direction given as a rule of action," especially "an injunction as to moral conduct," late 14c., from Old French percept, percet (12c.) and directly from Latin praeceptum "maxim, rule of conduct, order," noun use of neuter past participle of praecipere "give rules to, order, advise," literally "take beforehand," from prae "before" (see pre-) + capere (past participle captus) "to take," from PIE root *kap- "to grasp." For change of vowel, see biennial. Related: Preceptive; preceptory.
1580s, "word or phrase on an emblem explaining or emphasizing its symbolic significance; phrase or short sentence inscribed on something used to indicate the tenor of that to which it is attached," from Italian motto "a saying, legend attached to a heraldic design," from Late Latin muttum "a grunt; a word," from Latin muttire "to mutter, mumble, murmur" (see mutter). Meaning "proverbial pithy maxim adopted by someone as a rule of conduct" is from 1796. Motto-kiss "candy wrapped in fancy paper having a motto or scrap of poetry enclosed with it" is from 1858.