Accidents will happen (in the best-regulated families)

Accidents, accidents will happen—No less than seven brought into our infirmary yesterday.
[1763 G. Colman Deuce is in Him 1. 22]

Accidents will happen in the best regulated families.
[1819 ‘P. Atall’ Hermit in America i.]

‘Copperfield,’ said Mr. Micawber, ‘accidents will occur in the best-regulated families; and in families not regulated by‥the influence of Woman, in the lofty character of Wife, they must be expected with confidence, and must be borne with philosophy.’
[1850 Dickens David Copperfield xxviii.]

Accidents will happen in the best regulated families, and‥if you find you've got anything the matter with you,‥go and see a doctor right away.
[1939 W. S. Maugham Christmas Holiday x.]

No-one should underestimate the pain and suffering caused. However, the CPS [Crown Prosecution Service] has to recognise that, even in this determinedly scapegoat society, accidents do happen.
[2002 Country Life 14 Feb. 51]

Related to: misfortune

Bibliography of major proverb collections and works cited from modern editions is available here.