CLÉANTE: Most men are strangely made; they always stray
Out of the natural and proper way;
Rejecting reason’s bounds as limitations,
They range about amid their aberrations;
Even the noblest things they often mar
By forcing them and pushing them too far.

[Les hommes, la plupart, sont étrangement faits;
Dans la juste nature on ne les voit jamais:
La raison a pour eux des bornes trop petites,
En chaque caractère ils passent ses limites;
Et la plus noble chose, ils la gâtent souvent,
Pour la vouloir outrer et pousser trop avant.]

Molière (1622-1673) French playwright, actor [stage name for Jean-Baptiste Poquelin]

Tartuffe, or the Hypocrite [Le Tartuffe, ou L’Imposteur], Act 1, sc. 6 (1669) [tr. Frame (1967)]
    (Source)

(Source (French)). Alternate translations:

Men, generally are odd Creatures: They never keep up to true Nature. The Bounds of Reason are too narrow for them. In every Character they over-act their Parts, and the noblest Designs very often suffer in their Hands, because they will be running things into Extremes, and always carry things too far.
[tr. Clitandre (1672)]

Men, for the most part, are strange creatures, and never keep the right mean; reason's boundaries are too narrow for them; in every character they overact their parts; and they often spoil the noblest designs, because they exaggerate, and carry them too far.
[tr. Van Laun (1876)]

Men are really strange beings; they never keep to simple nature. The bounds of reason seem too narrow for them, and in every character they over-act their parts; they often spoil even the noblest thing by exaggeration.
[tr. Wall (1879)]

Men for the most part are strange creatures; they never see nature in its true light; the bounds of reason are too narrow for them. In every character they over-act their parts, and often spoil the noblest things; because they will run into extremes, and push matters too far.
[tr. Mathew (1890)]

Men, truly, are strange beings! They are never seen in their proper nature; reason's boundaries are too limited from them; in every character they over-act the part; and they often mar that which is most noble by too much exaggeration and by willful extremes.
[tr. Waller (1903)]

Men, for the most part, are strange creatures, truly!
You never find them keep the golden mean;
The limits of good sense, too narrow for them,
Must always be passed by, in each direction;
They often spoil the noblest things, because
They go too far, and push them to extremes.
[tr. Page (1909)]

Really, humanity is most peculiar!
Men won't remain in the mean middle way;
The boundaries of reason are too narrow.
They force their character beyond its limits,
And often spoil even most noble aims
By exaggeration, carrying things too far.
[tr. Bishop (1957)]

Ah, Brother, man's a strangely fashioned creature
Who seldom is content to follow Nature,
But recklessly pursues his inclination
Beyond the narrow bounds of moderation,
And often, by transgressing Reason's laws,
Perverts a lofty aim or noble cause.
[tr. Wilbur (1963), 1.5]

We humans are a curious lot
The fact is, few of us have got
A sense of Nature's golden mean,
We can't keep straight, we have to lean
To one, extreme and dangerous side;
The bounds of reason aren't that wide,
Staying within them is a feat
Beyond our scope -- you seldom meet
A man who'll tread its narrow way
If there's a chance for him to stray.
[tr. Bolt (2002)]

What strange creatures men are! They're always off balance; they think being reasonable is too limiting; they spoil what’s best by pushing things too far.
[tr. Steiner (2008), 1.5]

The majority of men are strangely made!
[tr. Campbell (2013)]