People are egregiously mistaken if they think they ever can attain to permanent popularity by hypocrisy, by mere outside appearances, and by disguising not only their language but their looks. True popularity takes deep root and spreads itself wide; but the false falls away like blossoms; for nothing that is false can be lasting.

[Quodsi qui simulatione et inani ostentatione et ficto non modo sermone, sed etiam voltu stabilem se gloriam consequi posse rentur, vehementer errant. Vera gloria radices agit atque etiam propagatur, ficta omnia celeriter tamquam flosculi decidunt, nee simulatum potest quicquam esse diuturnum.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher
De Officiis [On Duties; On Moral Duty; The Offices], Book 2, ch. 12 / sec. 43 (44 BC) [tr. Edmonds (1865)]
    (Source)

(Source (Latin)). Alternate translation:

Those people therefore are highly mistaken, who think of obtaining a solid reputation by vain shows and hypocritical pretences; by composed countenances and studied forms of words: for true glory takes deep root, and grows and flourishes more and more; but that which is only in show and mere outside, quickly decays and withers like flowers; nor can anything be lasting that is only counterfeit.
[tr. Cockman (1699)]

But if any suppose, that they can obtain a stable reputation by pretences, empty ostentation, hypocritical conversation, and even artificial looks, they are extremely mistaken. True fame takes deep root, and extends its shoots. Every counterfeit appearance, like blossoms, quickly falls off; and no pretense can be lasting.
[tr. McCartney (1798)]

If there be those who think to obtain enduring fame by dissembling and empty show, and by hypocrisy, not only of speech, but of countenance also, they are utterly mistaken. True fame strikes its roots downward, and sends out fresh shoots; all figments fall speedily, like blossoms, nor can anything feigned be lasting.
[tr. Peabody (1883)]

It is a delusion to suppose that glory can be founded on dissimulation, vain ostentation, and studied words and looks. True glory strikes root and spreads, everything unreal soon falls like the blossoms, a lie cannot last.
[tr. Gardiner (1899)]

True glory strikes roots, and grows: ill-founded reputations, like flowers, soon wither, nor can anything last long which is based on pretence.
[ed. Harbottle (1906)]

For if anyone thinks that he can win lasting glory by pretence, by empty show, by hypocritical talk and looks, he is very much mistaken. True glory strikes deep root and spreads its branches wide; but all pretences soon fall to the ground like fragile flowers, and nothing counterfeit can be lasting.
[tr. Miller (1913)]

If anyone thinks he can attain lasting glory by mimicry, by empty shows, by pretense in his looks and his conversation, he is far from correct. Genuine glory puts down roots and even sends out new growth; any pretense dies down quickly, like fragile flowers. Nothing simulated can be long-lasting.
[tr. Edinger (1974)]