For Want of a Nail


"For Want of a Nail" is a proverb, having numerous variations over several centuries, reminding that seemingly unimportant acts or omissions can have grave and unforeseen consequences.

Analysis

The proverb has come down in many variations over the centuries. It describes a situation in which a failure to predict or correct some initially small dysfunction leads by successively more critical stages to an egregious outcome. The rhyme's implied small difference in initial conditions is the lack of a spare horseshoe nail, relative to a condition of its availability. At a more literal level, it expresses the importance of military logistics in warfare.
Such chains of causality are perceived only in hindsight. No one ever lamented, upon seeing his unshod horse, that the kingdom would eventually fall because of it.
Related sayings are "A stitch, in time, saves nine" and "An ounce of prevention is worth a pound of cure". A somewhat similar idea is referred to in the metaphor known as the camel's nose.

Historical references

The proverb is found in a number of forms, beginning as early as the 13th century:
Along with the long history of the proverb listed above, it has continued to be referenced since the mid 20th century in modern culture. Examples include:

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