There is but two ways of rising in the World, by your own Industry, and another's Weakness.
[Bullord ed. (1696)]

There are only two ways of rising in the World, by your own Industry, or by the Weakness of others.
[Curll ed. (1713)]

There are but two ways of rising in the World, by your own Industry, or the Weakness of others.
[Browne ed. (1752)]

There are only two ways of getting on in the world: either by one's own cunning efforts, or by other people's foolishness.
[tr. Stewart (1970)]

Variants:

• "Every organisation behaves as if it is run by secret agents of its opponents."
• "The behavior of any organization can best be predicted on the assumption that it is headed by a secret cabal of its enemies."

You, more in age
And more in excellence, know well, the outrays that engage
All young men’s actions; sharper wits, but duller wisdoms, still
From us flow than from you.
[tr. Chapman (1611), l. 505ff]

Thou know’st how rash is youth, and how propense
To pass the bounds by decency prescribed,
Quick, but not wise.
[tr. Cowper (1791), l. 729ff]

Thou knowest of what sort are the errors of a youth; for his mind is indeed more volatile, and his counsel weak.
[tr. Buckley (1860)]

Thou know’st the o’er-eager vehemence of youth,
How quick in temper, and in judgement weak.
[tr. Derby (1864)]

Thou dost know
The faults to which the young are ever prone;
The will is quick to act, the judgment weak.
[tr. Bryant (1870)]

Thou knowest how a young man's transgressions come about, for his mind is hastier and his counsel shallow.
[tr. Leaf/Lang/Myers (1891)]

You know how easily young men are betrayed into indiscretion; their tempers are more hasty and they have less judgement.
[tr. Butler (1898)]

Thou knowest of what sort are the transgressions of a man that he is young, for hasty is he of purpose and but slender is his wit.
[tr. Murray (1924), l. 589-90]

It is easy for a youngster to go wrong from hastiness and lack of thought.
[tr. Graves, The Anger of Achilles (1959)]

You know a young man may go out of bounds:
his wits are nimble, but his judgment slight.
[tr. Fitzgerald (1974)]

Well you know how the whims of youth break all the rules.
Our wits quicker than wind, our judgment just as flighty.
[tr. Fagles (1990)]

Full text.

Variants sometimes seen:

• The man who sets out to carry a cat by its tail learns something that will always be useful and which never will grow dim or doubtful.
• A man who carries a cat by the tail learns something he can learn in no other way.