MEANING

Literally meaning as many men, so many opinions, the Latin proverb quot homines tot sententiæ expresses the fact that there is considerable diversity of opinion, and the difficulty of bringing about agreement.

ORIGIN

The saying first appeared in an English text in Prouerbes or adagies with newe addicions gathered out of the Chiliades of Erasmus (London, 1539), a condensed rendering by Richard Taverner (circa 1505-1575) of Adagiorum chiliades (Thousands of Proverbs), originally written in Latin by the Dutch humanist Desiderius Erasmus (circa 1469-1536):

Quot homines, tot sentenciae.
So many men, so many wyttes. So many heades, so many iudgementes. Thapostle Paule not forgetfull herof aduertyseth vs, that for the excludynge of contencion we suffer euery man to abunde in hys owne sence, whose counsayle yf oure diuines in Christendome wolde followe, there shulde not be at thys day so great dissensiō in ye church in maters of smal weyght. For there be many thynges which without daunger of the christen relygyon maye be vnknowen wel ynough.

The following is the translation of the adage composed by Erasmus—original text at the end of this post:

adapted from The Adages of Erasmus, selected by William Barker (University of Toronto Press – 2001):
Quot homines, tot sententiae – As many men, so many opinions
Nothing is more widely known even today than this saying of Terence, “as many men, so many opinions”, and in the same author there is a similar phrase, “every man has his own way”. Persius also:
Men are of a thousand kinds, and diverse the colour of their lives;
Each has his own desires; no two offer the same prayer.

In the same class is that remark in an epigram that one may find people who are willing to yield in the matter of family acres, but not one who will give way on a matter of opinion. Horace adds an elegant metaphor:
Three guests I have, of wishes quite contrary;
As their tastes differ, so their orders vary.

It was Horace, too, who devoted the first ode of all to the subject of this proverb, i.e. that different people are led by different interests, that some have one thing at heart and some another. Terence, in Phormio, plays upon this in jest when he says of three advisers, “the first says yes, the second says no, and the third says ‘let’s think about it’”. St Paul the Apostle seems to have made a reference to this when he says that for the putting aside of strife, we should allow every man to have his own convictions. If the general run of theologians had listened to this advice, there would not now be such fierce contention about little questions of no moment at all; for there certainly are some things of which one may remain in ignorance without any lack of piety. The same thought is expressed at greater length by Euripides in the Phœnissae:
If what were fair and wise were so to all
Disputing strife would not exist for men,
But now for mortals naught is ‘like’ nor ‘same’,
Only the words may happen to agree,
In deed and fact no likeness can be found.

Again in Hyppolitus Crowned:
This man, this God, is after their own heart
To some, not so to others.

Homer thought of this in the Odyssey, book 14:
For one man takes delight in certain things,
Another in others.

The proverb, therefore, is from Phormio (161 BC), a play by the Roman comic dramatist Terence (Publius Terentius Afer – circa 190-159 BC):

– Demipho: dic nunc, Hegio.
– Hegio: ego sedulo hunc dixisse credo; verum itast,
quot homines tot sententiæ: suo quoique mos.
     translation:
– Demipho: Say now, Hegio.
– Hegio: I believe that he has spoken with due deliberation; but it is the fact,
As many men, so many opinions: to everyone his own way.

The Roman statesman, orator and writer Marcus Tullius Cicero (106-43 BC) quoted Terence in De finibus bonorum et malorum (On the ends of good and evil):

Sed “quot homines, tot sententiæ”; falli igitur possumus.
     translation:
However, “as many men, so many opinions”; so it is possible that I am mistaken.

The English rendering of the proverb has often been so many men, so many minds, as in Theodulia, or, A just defence of hearing the sermons and other teaching of the present ministers of England (London, 1667), by the Baptist minister John Tombes (1602-76):

To speak truth, the application of this Text in that manner, as it is by some, as if the Apostle did forbid us the use of any thing though in different in it self, when it appears as evil to another, without any further restraint, is very absurd and so unreasonable, as that it will bring a yoke upon mens consciences impossible to be born, sith [= since] there is scarce any thing a man can do, but some or other Infidel or Christian, weak or strong in the faith; Orthodox or Superstitious, will think it to be evil; that saying by experience being found true, quot homines tot sententiæ, so many men, so many minds. 

original text by Erasmus:

Quot homines, tot sententiae
Nihil vel hodie vulgo tritius est quam haec Terentiana sententia: Quot homines, tot sententiae. Cui similis est apud eundem et illa Suus cuique mos erat. Persius item:
Mille hominum species et rerum discolor vsus.
Velle suum cuique est nec voto viuitur vno.

Eodem pertinet et illud epigrammaticum, quo dictum est inueniri qui non recusent agris paternis cedere, qui velit ingenio cedere, reperiri neminem. Horatius decentissimam addidit allegoriam:
Tres mihi conuiuae prope dissentire videntur,
Poscentes vario multum diuersa palato.

Idem primam omnium odam huius argumento sententiae conscripsit aliis studiis alios duci, aliis alia cordi esse. Allusit facetissime Terentius in Phormione, cum e tribus aduocatis primus ait, secundus negat, tertius deliberandum censet. Huc allusisse videtur et diuus Paulus apostolus, cum admonet, vt ad praecludendam aemulationem sinamus vnumquenque in suo sensu abundare. Cui consilio si theologorum vulgus auscultaret, non esset hodie tanta digladiatio de nihili quaestiunculis; sunt enim omnino quaedam quae citra pietatis dispendium ignorari possunt. Eam sententiam Euripides in Phoenissis latius explicuit:
Εἰ πᾶσι ταὐτὸ καλὸν ἔφυ σοφόν θ᾽ ἅμα,
Οὐκ ἦν ἂν ἀμφίλεκτος ἀνθρώποις ἔρις·
Νῦν δ᾽ οὔθ᾽ ὅμοιον οὐδὲν οὔτ᾽ ἴσον βροτοῖς,
Πλὴν ὀνομάσαι· τὸ δ᾽ ἔργον οὐκ ἔστίν τόδε, id est
Cunctis idem si pulchrum et egregium foret,
Nulla esset anceps hominibus contentio;
At nunc simile nil, nil idem mortalibus,
Nisi verba forsan inter istos concinunt;
At re tamen factisque conuenit nihil.

Idem in Hippolyto coronato:
Ἄλλοισιν ἄλλος θεῶν τε κ᾽ ἀνθρώπων μέλει, id est
Hic his, hic illis, et homo cordi est, et deus.

Huc respexit Homerus in Odysseae ξ:
Ἄλλος γάρ τ᾽ ἄλλοισιν ἀνὴρ ἐπιτέρπεται ἔργοις, id est
Nanque aliis aliae res arridentque placentque.