A dictionary of Proverbs (Oxford Paperback Reference)

OPPORTUNITY never knocks twice at any man’s door
Fortune occurs instead of opportunity in earlier forms of the saying. Several quotations below represent slightly different ideas based on the original proverb. In quots. 1809 and 1981, Opportunity is said to knock once or more, but in other quotations, once only. Cf. early 15th- cent Fr. il n’est chance qui ne retourne, there is no opportunity which comes back again.

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  1567 G. FENTON Bandello 216 Fortune once in the course of our life, dothe put into our handes the offer of a good torne. 1809 Port Folio (Philadelphia) Nov. 431 Fortune knocks once, at least, at every man’s door. 1889 W. F. BUTLER C. G. Gordon iii. Fate, it is said, knocks once at every man’s door. . . Gordon had just passed his thirtieth year when Fortune.. knocked at.. the door which was to lead him to fame. 1891 J. J. INGALLS Opportunity in Truth (NY) 19 Feb. 171 [Opportunity] knock unbidden once at every gate! If sleeping, wake: if feasting rise before I turn away.. [for] I return no more! 1941 ‘P. WENTWORTH’ Unlawful Occasions xxiv. It was an opportunity with a capital O, and if she threw it away it would never come back again. Opportunity never knocks twice at any man’s door. 2001 Washington Post 18 Nov. F2 Experts are uniquely vulnerable to one weakness: Opportunity may knock only once, but the temptation to try to make a contract the hard way—and make the newspapers—is always pounding at the expert’s door. opportunity
  

opportunity see also ENGLAND’S difficulty is Ireland’s opportunity; MAN’S extremity is God’s opportunity.
opposite see DREAMS go by contraries.
orders see OBEY orders, if you break owners.
orphan see SUCCESS has many fathers, while failure is an orphan.
OTHER times, other manners
The proverb occurs in various forms and languages: cf. PINDAR Fragment ccxxv. (Bowra), Ithink different thoughts at different times; Fr. autres temps,
autres ma’urs, other times, other customs.

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