Straw that broke the camel's back

The idiom the straw that broke the camel's back, alluding to the proverb "it is the last straw that breaks the camel's back", describes the seemingly minor or routine action which causes an unpredictably large and sudden reaction, because of the cumulative effect of small actions.

This gives rise to the phrase "the last straw" or "the final straw", meaning the last in a line of unacceptable occurrences, provoking a seemingly sudden strong reaction.

Other variants are:

Variants were discussed in several numbers of Notes and Queries in 1893.

The same sentiment is also expressed by the phrase "the last drop makes the cup run over", first found as "When the Cup is brim full before, the last (though least) added drop is charged alone to be the cause of all the running over" (1655). Furthermore, in other languages, the use of the drop is the common way to express the same evocative sentiment. For example in Italian, Spanishand French is the last drop that makes the vase to spill over.

The phrase has been compared with Seneca's discussion on why death is not to be feared. Starting with a mention of the commonplace "we do not suddenly fall on death, but advance towards it by slight degrees; we die every day" (non repente nos in mortem incidere, sed minutatim procedere; cotidie morimur), Seneca compares life to a water-clock:

It is not the last drop that empties the water-clock, but all that which previously has flowed out; similarly, the final hour when we cease to exist does not of itself bring death; it merely of itself completes the death-process. We reach death at that moment, but we have been a long time on the way.

Quemadmodum clepsydram non extremum stillicidium exhaurit, sed quicquid ante defluxit, sic ultima hora, qua esse desinimus, non sola mortem facit, sed sola consummat; tunc ad illam pervenimus, sed diu venimus.

In contrast to the imagery of the "last straw", which emphasizes dramatic final result, Seneca emphasizes the continuity of the final hour of life with all the hours that have come before.

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