Is your cucumber bitter? Throw it away. Are there briars in your path? Turn aside. That is enough. Do not go on to say, “Why were things of this sort ever brought into the world?” The student of nature will only laugh at you; just as a carpenter or a shoemaker would laugh, if you found fault with the shavings and scraps from their work which you saw in the shop.

[Σίκυος πικρός; ἄφες. βάτοι ἐν τῇ ὁδῷ; ἔκκλινον. ἀρκεῖ, μὴ προσεπείπῃς: τί δὲ καὶ ἐγένετο ταῦτα ἐν τῷ κόσμῳ; ἐπεὶ καταγελασθήσῃ ὑπὸ ἀνθρώπου φυσιολόγου, ὡς ἂν καὶ ὑπὸ τέκτονος καὶ σκυτέως γελασθείης καταγινώσκων ὅτι ἐν τῷ ἐργαστηρίῳ ξέσματα καὶ περιτμήματα τῶν κατασκευαζομένων ὁρᾷς.]

Marcus Aurelius (AD 121-180) Roman emperor (161-180), Stoic philosopher

Meditations [To Himself; Τὰ εἰς ἑαυτόν], Book 8, ch. 50 (8.50) (AD 161-180) [tr. Staniforth (1964)]
    (Source)

(Source (Greek)). Alternate translations:

Is the cucumber bitter? set it away. Brambles are in the way? avoid them. Let this suffice. Add not presently speaking unto thyself, What serve these things for in the world? For, this, one that is acquainted with the mysteries of nature, will laugh at thee for it; as a carpenter would or a shoemaker, if meeting in either of their shops with some shavings, or small remnants of their work, thou shouldest blame them for it.
[tr. Casaubon (1634), 8.48]

Does your Cucumber taste bitter? Let it alone. Are there Brambles in your way? Avoid them then. Thus far you are well: But then don't ask what does the World with such stuff as this is? This is to be too Bold, and Impertinent; And a Natural Philosopher would laugh at you: This Expostulation is just as Wise as it would be to find fault with a Carpenter for having Saw-dust, or a Taylor Shreds in his Shop.
[tr. Collier (1701)]

Is the cucumber bitter? Throw it away. Are there thorns in the way? Walk aside. That is enough. Don’t be adding; “Why were such things in the universe?” A naturalist would laugh at you, as would a carpenter, too, or a shoe-maker, if you were finding fault, because shavings and parings of their Works are lying about in their work-houses.
[tr. Hutcheson/Moor (1742)]

Is the cucumber which you are eating, bitter? let it alone. Are there thorns int he path where you are walking? avoid them. This is sufficient for your particular purpose. But do not peevishly ask, "why are such things permitted in the world?" For a naturalist would laugh at you; and with as much reason as a carpenter or a tailor would do, if you should blame them for having shavings or shreds in their respective shops.
[tr. Graves (1792), 8.49]

A cucumber is bitter -- Throw it away. -- There are briers in the road -- Turn aside from them. -- This is enough. Do not add, And why were such things made in the world? For thou wilt be ridiculed by a man who is acquainted with nature, as thou wouldst be ridiculed by a carpenter and shoemaker if thou didst find fault because thou seest in their workshop shavings and cuttings from the things which they make.
[tr. Long (1862)]

Does your cucumber taste bitter? Let it alone. Are there brambles in your way? Avoid them then. Thus far you are well. But, then, do not ask what does the world with such things as this, for a natural philosopher would laugh at you. This expostulation is just as wise as it would be to find fault with a carpenter for having saw-dust, or a tailor shreds in his shop.
[tr. Collier/Zimmern (1887)]

The gourd is bitter: drop it then! There are brambles in the path: then turn aside! It is enough. Do not go on to argue, Why pray have these things a place int he world? The natural philosopher would laugh at you, just as a carpenter or cobbler would laugh, if you began finding fault because you saw chips or parings lying about their shop.
[tr. Rendall (1898)]

Is the gourd bitter? Put it from you. Are there thorns in the way? Walk aside. That is enough. Do not add, “Why were such things brought into the world?” The naturalist would laugh at you, just as would a carpenter or a shoemaker, if you began fault-finding because you saw shavings and parings from their work strewn about the workshop.
[tr. Hutcheson/Chrystal (1902)]

The gherkin is bitter. Toss it away. There are briars in the path. Turn aside. That suffices, and thou needest not to add: Why are such things found in the world? For thou wouldst be a laughing stock to any student of nature; just as thou wouldst be laughed at by a carpenter and a cobbler if thou tookest them to task because in their shops are seen sawdust and parings from what they are making.
[tr. Haines (Loeb) (1916)]

The cucumber is bitter? Put it down. There are brambles in the path? Step to one side. That is enough, without also asking: "Why did these things come into the world at all?" Because the student of Nature will ridicule the question, exactly as a carpenter or cobbler would laugh at you if you found fault because you see shavings and clippings from their work in their shops.
[tr. Farquharson (1944)]

The cucumber is bitter? Cast it aside. There are brambles in the path? Step out of the way. That will suffice, and you need not ask in addition, "Why did such things ever come into the world?" For anyone who has made a study of nature would laugh at you, just as a carpenter or shoemaker would laugh at you if you criticised them because you could see in their workshop the shavings or parings form what they were working on.
[tr. Hard (1997 ed.)]

The cucumber is bitter? Then throw it out.
There are brambles in the path? Then go around them.
That's all you need to know. Nothing more. Don't demand to know "why such things exist." Anyone who understands the world will laugh at you, just as a carpenter would if you seemed shocked at finding sawdust in his workshop, or a shoemaker at scraps of leather left over from work.
[tr. Hays (2003)]

A bitter cucumber? Throw it away. Brambles in the path? Go round them. That is all you need, without going on to ask, "So why are these things in the world anyway?" That question would be laughable to a student of nature, just as any carpenter or cobbler would laugh at you if you objected to the sight of shavings or off-cuts from their work on the shop floor.
[tr. Hammond (2006)]

The cucumber is bitter? Then cast it aside. There are brambles in the path? Step out of the way. That will suffice, and you need not ask in addition, "Why did such things ever come into the world?" For anyone who has made a study of nature would laugh at you, just as a carpenter or shoemaker would laugh at you if you criticized them because you could see in their workshop the shavings or parings from the items that they were working on.
[tr. Hard (2011 ed.)]