Quotations about   self-control

So also anybody can become angry — that is easy, and so it is to give and spend money; but to be angry with or give money to the right person, and to the right amount, and at the right time, and for the right purpose, and in the right way — this is not within everybody’s power and is not easy; so that to do these things properly is rare, praiseworthy, and noble.

[οὕτω δὲ καὶ τὸ μὲν ὀργισθῆναι παντὸς καὶ ῥᾴδιον, καὶ τὸ δοῦναι ἀργύριον καὶ δαπανῆσαι: τὸ δ᾽ ᾧ καὶ ὅσον καὶ ὅτε καὶ οὗ ἕνεκα καὶ ὥς, οὐκέτι παντὸς οὐδὲ ῥᾴδιον: διόπερ τὸ εὖ καὶ σπάνιον καὶ ἐπαινετὸν καὶ καλόν.]

Aristotle (384-322 BC) Greek philosopher
Nicomachean Ethics [Ἠθικὰ Νικομάχεια], Book 2, ch. 9 (2.9, 1109a.27) (c. 325 BC) [tr. Rackham (1934)]
    (Source)

(Source (Greek)). Alternate translations:

Just so to be angry, to give money, and be expensive, is what any man can do, and easy: but to do these to the right person, in due proportion, at the right time, with a right object, and in the right manner, this is not as before what any man can do, nor is it easy; and for this cause goodness is rare, and praiseworthy, and noble.
[tr. Chase (1847)]

And so, too, to get angry is an easy matter, and in any man's power; or to give away money or to spend it: but to decide to whom to give it, and how large a sum, and when, and for what purpose, and how, is neither in every many's power, nor an easy matter. And hence it is that excellence herein is rare and praiseworthy and noble.
[tr. Williams (1869), sec. 37]

So too anybody can get angry -- that is an easy matter -- and anybody can give or spend money, but to give it to the right persons, to give the right amount of it and to give it at the right time and for the right cause and in the right way, this is not what anybody can do, nor is it easy. That is the reason why it is rare and laudable and noble to do well.
[tr. Welldon (1892)]

Thus anyone can be angry -- that is quite easy; anyone can give money away or spend it: but to do these things to the right person, to the right extent, at the right time, with the right object, and in the right manner, is not what everybody can do, and is by no means easy; and that is the reason why right doing is rare and praiseworthy and noble.
[tr. Peters (1893)]

So, too, anyone can get angry -- that is easy -- or give or spend money; but to do this to the right person, to the right extent, at the right time, with the right motive, and in the right way, that is not for everyone, nor is it easy; wherefore goodness is both rare and laudable and noble.
[tr. Ross (1908)]

In the same way, getting angry is also something everyone can do and something easy, as is giving or spending money. Determining whom to give it to, though, and how much, when, for the sake of what, and in what way -- that is no longer something everyone can do or something easy. That is why doing it well is a rare thing and a praiseworthy and noble one.
[tr. Reeve (1948)]

So, too, anyone can get angry or give money or spend it, and it is easy. But to give to the right person, the right amount, at the right time, for the right purpose, and in the right manner, this is not something anyone can do nor is it easy to do; and it is in view of this that excellence is rare and praiseworthy and noble.
[tr. Apostle (1975)]

So too it is easy to get angry -- anyone can do that -- or to give and spend money; but to feel or act towards the right person to the right extent at the right time for the right reason in the right way -- that is not easy, and it is not everyone that can do it. Hence to do these things well is a rare, laudable, and fine achievement.
[tr. Thomson/Tredennick (1976)]

So too anyone can get angry, or give and spend money -- these are easy, but doing them in relation to the right person, in the right amount, at the right time, with the right aim in view, and in the right way -- that is not something anyone can do, nor is it easy. This is why excellence in these things is rare, praiseworthy, and noble.
[tr. Crisp (2000)]

And so too, to become angry belongs to everyone and is an easy thing, as is also giving and spending money; but to whom [one ought to do so], how much, when for the sake fo what, and how -- these no longer belong to everyone nor are easy. Thus in fact acting well is rare, praiseworthy, and noble.
[tr. Bartlett/Collins (2011)]

Note that some translations paraphrase this only to speak of anger, e.g., Edith M. Leonard, et al., The Child: At Home and School (1944):

Anybody can become angry, that is easy; but to be angry with the right person, and to the right degree, and at the right time, for the right purpose, and in the right way, that is not within everybody's power and is not easy.