MESSENGER: I have not now first learn’d that all
Th’ affairs of mortal men are a mere shadow:
Nor would I fear to say that those, who most
Boast of their wisdom and their deep research,
The widest in the paths of folly stray.
No mortal man is happy: if the tide
Of wealth flows in upon him, one may be
More fortunate than others, happy never.

[ἌΓΓΕΛΟΣ: τὰ θνητὰ δ᾽ οὐ νῦν πρῶτον ἡγοῦμαι σκιάν,
οὐδ᾽ ἂν τρέσας εἴποιμι τοὺς σοφοὺς βροτῶν
δοκοῦντας εἶναι καὶ μεριμνητὰς λόγων
τούτους μεγίστην μωρίαν ὀφλισκάνειν.
θνητῶν γὰρ οὐδείς ἐστιν εὐδαίμων ἀνήρ:
ὄλβου δ᾽ ἐπιρρυέντος εὐτυχέστερος
ἄλλου γένοιτ᾽ ἂν ἄλλος, εὐδαίμων δ᾽ ἂν οὔ.]

Euripides (485?-406? BC) Greek tragic dramatist

Medea [Μήδεια], l. 1224ff (431 BC) [tr. Potter (1814)]
    (Source)

Having brought word to Medea of Glauce and Creon's tortured deaths.

(Source (Greek)). Other translations:

Not now for the first time do I esteem
Human affairs a shadow: without fear
Can I pronounce, they who appear endued
With wisdom and most plausibly trick out
Specious harangues, deserve to be accounted
The worst of fools. The man completely blest
Exists not. Some in overflowing wealth
May be more fortunate, but none are happy.
[tr. Wodhull (1782)]

But not now first I count the lot of man
A passing shadow: and I might say those
Of mortals who are very seeming wise
And fret themselves with learnings, those are they
Who make them guilty of the chiefest folly;
But no one mortal is a happy man,
Though, riches flooding in, more prosperous
One than another grow; yet none is happy.
[tr. Webster (1868)]

Not now for the first time I think this human life a shadow; yea, and without shrinking I will say that they amongst men who pretend to wisdom and expend deep thought on words do incur a serious charge of folly; for amongst mortals no man is happy; wealth may pour in and make one luckier than another, but none can happy be.
[tr. Coleridge (1891)]

But the affairs of mortals not now for the first time I deem a shadow, and I would venture to say that those persons who seem to be wise and are researchers of arguments, these I say, run into the greatest folly. For no mortal man is happy; but wealth pouring in, one man may be more fortunate than another, but happy he can not be.
[tr. Buckley (1892)]

But man's lot now, as oft, I count a shadow,
Nor fear to say that such as seem to be
Wise among men and cunning in speech-lore,
Even these are chargeable with deepest folly;
For among mortals happy man is none.
In fortune's flood-tide might a man become
More prosperous than his neighbour: happy? -- no!
[tr. Way (Loeb) (1894)]

Long ago
I looked upon man's days, and found a grey
Shadow. And this thing more I surely say,
That those of all men who are counted wise,
Strong wits, devisers of great policies,
Do pay the bitterest toll. Since life began,
Hath there in God's eye stood one happy man?
Fair days roll on, and bear more gifts or less
Of fortune, but to no man happiness.
[tr. Murray (1906)]

Our human life I think and have thought a shadow,
And I do not fear to say that those who are held
Wise among men and who search the reasons of things
Are those who bring the most sorrow on themselves.
For of mortals there is no one who is happy.
If wealth flows in upon one, one may be perhaps
Luckier than one’s neighbor, but still not happy.
[tr. Warner (1944)]

As for human life,
It is a shadow, as I have long believed. And this
I say without hesitation: those whom most would call
Intelligent, the propounders of wise theories --
Their folly is of all men's the most culpable.
Happiness is a thing no man possesses. Fortune
May come now to one man, now to another, as
Prosperity increases; happiness never.
[tr. Vellacott (1963)]

I have often considered the human condition a shadow,
And I would not hesitate to say that those
Who seem to be wise and concern themselves with learning,
These risk being called the biggest fools.
For no mortal is truly blessed;
When wealth flows one may have more luck
Than another, but is not for that reason blessed.
[tr. Podlecki (1989)]

As for our mortal life, this is not the first time that I have thought it to be a shadow, and I would say without any fear that those mortals who seem to be clever and workers-up of polished speeches are guilty of the greatest folly. For no mortal ever attains to blessedness. One may may be luckier than another when wealth flows his way, but blessed never.
[tr. Kovacs (Perseus); Kovacs / Zhang / Rogak]

As for our mortal life, this is not the first time that I have thought it to be a shadow, and I would say without any fear that those mortals who seem to be clever and crafters of polished speeches are guilty of the greatest folly. For no mortal ever attains to blessedness. One may may be luckier than another when wealth flows his way, but blessed never.
[tr. Kovacs (Loeb) (1994)]

As for the life of man,. I think and have often thought it is a shadow. I would not hesitate to say that those who pass for thinkers on this earth, for men of subtle reasoning, are guilty of being the greatest fools. For no one in this life of ours knows happiness. When fortune’s tide flows towards him, one man may surpass another in prosperity, but you should not call him happy.
[tr. Davie (1996)]

As for me, I’ve said it often: All things accomplished by mortals are mere shadows. Nor am I afraid to say that those people who consider themselves philosophers and know the art of spinning good words and say that man can live in happiness, well, those men are stupid!
Wealth may make your life a little better than that of your neighbour but it will not give you happiness.
[tr. Theodoridis (2004)]

Not for the first time I find our lives are a shadow,
and I am not afraid to say that people who think
they have everything figured out and are masters of logic
— they are responsible for the greatest folly.
No human being is happy.
Strike it rich and you are luckier
than your neighbor — but happy, never.
[tr. Luschnig (2007)]

As for human life,
it seems to me, and not for the first time,
nothing but shadows. And I might say,
without feeling any fear, those mortals
who seem wise, who prepare their words with care,
are guilty of the greatest foolishness.
Among human beings no one is happy.
Wealth may flow in to produce a man
more lucky than another, but no man,
is ever happy, no one.
[tr. Johnston (2008)]

This is not the first time that I find human affairs to be a shadowy, uncertain thing. Without any hesitation I would say that those among men who have a reputation for being sophoi, and who expend deep thought on reasonings, do incur the greatest charge of folly. No man among mortals is happy [eudaimōn]. Prosperity [olbos] may pour in and make one luckier than another, but not eudaimōn.
[tr. Coleridge / Ceragioli / Nagy / Hour25]