No man rules safely unless he is willing to be ruled. No man commands safely unless he has learned well how to obey.

[Nemo secure apparet nisi qui libenter latet. Nemo secure præcipit nisi qui obedire didicit.]

Thomas à Kempis (c. 1380-1471) German-Dutch priest, author

The Imitation of Christ [De Imitatione Christi], Book 1, ch. 20, v. 2 (1.20.2) (c. 1418-27) [tr. Croft/Bolton (1940)]
    (Source)

See also Cicero. (Source (Latin)). Alternate translations:

No man is sure in prelacy, but that he would gladly be a subject: no, none may surely command, but he that hath learned gladly to obey
[tr. Whitford/Raynal (1530/1871)]

No man is secure in high position save he who would gladly be a subject. No man can firmly command save he who has learned gladly to obey.
[tr. Whitford/Gardiner (1530/1955)]

No man ruleth safely but he that is ruled willingly, no man securely doth command, but he that hath learned readily to obey.
[tr. Page (1639), 1.20.9]

No Man is fit to govern who hath not learned how to obey.
[tr. Stanhope (1696; 1706 ed.)]

No man can safely govern, that would not cheerfully become subject; no man can safely command, that has not truly learned to obey.
[tr. Payne (1803), 1.20.4]

No man ruleth safely, but he that is willingly ruled. No man securely doth command, but he that hath learned readily to obey.
[ed. Parker (1841)]

No man can safely govern, that would not willingly be governed; no man can safely command, that has not well learned to obey.
[tr. Dibdin (1851), 1.20.3]

No man is safe to govern, but he who would rather live in subjection. No man is safe to command, but he who has learned well how to obey.
[ed. Bagster (1860)]

No man safely ruleth but he who loveth to be subject. No man safely commandeth but he who loveth to obey.
[tr. Benham (1874)]

No man doth safely rule, but he that is glad to be ruled. No man doth safely rule, but he that hath learned gladly to obey.
[tr. Anon. (1901)]

No one is safely set above who would not cheerfully be subject. No one safely gives orders but he who has thoroughly learned to obey.
[tr. Daplyn (1952)]

No man can safely command, unless he who has learned to obey well.
[tr. Sherley-Price (1952)]

Never trust yourself [...] to come to the front, unless you would sooner be at the back; to give orders, unless you know how to obey them.
[tr. Knox-Oakley (1959), 1.20(b)]

No one can safely be in command, but the man who has learned complete obedience.
[tr. Knott (1962)]

No one governs with safety who is unwilling to be governed. No one gives commands with safety who has not learned well how to obey.
[tr. Rooney (1979)]

No one leads securely except the person who freely serves.
[tr. Creasy (1989)]