只因少了一顆釘

只因少了一顆釘（英語：For Want of a Nail）是一首韻文，說明小的行動可能會導致大後果。最早可能源於13世紀日耳曼地區詩人佛萊登的作品。

For Want of a Nail

For want of a nail the shoe was lost.
少了釘子，失了蹄鐵。
For want of a shoe the horse was lost.
少了蹄鐵，失了戰馬。
For want of a horse the rider was lost.
少了戰馬，失了騎士。
For want of a rider the message was lost.
少了騎士，失了情報。
For want of a message the battle was lost.
少了情報，失了勝仗。
For want of a battle the kingdom was lost.
少了勝仗，失了王國。
And all for the want of a horseshoe nail.
這全因少了個馬蹄釘。

分析

此一歐洲中世紀的寓言詩是用來提醒「微小的失誤可能帶來巨大的後患」。最早的版本比較簡單，只說到「少了騎士，失了城堡」，後世則衍生許多版本。

另見

• 蝴蝶效應
• 破窗效應
• 因果
• 混沌理論
• 多米諾骨牌效應
• 諺語
• 民俗學
• 韻文

參考文獻

• Benjamin Franklin, Poor Richards Almanack, June 1758, The Complete Poor Richard Almanacks, facsimile ed., vol. 2, pp. 375, 377
• G. Herbert, Outlandish Proverbs, c. 1640, no. 499
• Oxford Dictionary of Nursery Rhymes, ed. Iona and Peter Opie, Oxford 1951, pg 324

外部連結

• Famous Quotes UK （頁面存檔備份，存於互聯網檔案館） (Retrieved 14-Feb-2008)
• "For want of a nail" at Everything2.com （頁面存檔備份，存於互聯網檔案館） (Retrieved 14-Feb-2008)
• The Lorenz Butterfly (Retrieved 14-Feb-2008)
• JSTOR:For Want of a Nail, E. J. Lowe, Analysis, Vol. 40, No. 1 (Jan., 1980), pp. 50–52 (Retrieved 14-Feb-2008)
• James S. Robbins on 9/11 Commission published April 09, 2004 by National Review Online "For want of a nail:Lady Condoleezza on the battle of the Saracens." （頁面存檔備份，存於互聯網檔案館） (Retrieved 14-Feb-2008)
• Benjamin Franklin (1706–1790), U.S. statesman, writer. Poor Richard’s Almanac, preface (1758). （頁面存檔備份，存於互聯網檔案館） (Retrieved 14-Feb-2008)