The idea is Aquinas’s, but the wording is not. In Summa Theologiae I-II, q. 2, a. 5 he writes that “a captain does not intend as a last end, the preservation of the ship entrusted to him, since a ship is ordained to something else as its end, viz. to navigation” (Dominican translation ↗). The punchline about keeping the ship “in port forever” is not in the text. It is an unsourced modern rewording.
“If the highest aim of a captain were to preserve his ship, he would keep it in port forever” is a later paraphrase, not Aquinas’s words. Aquinas, Summa Theologiae I-II, q. 2, a. 5 (Dominican translation): “Hence a captain does not intend as a last end, the preservation of the ship entrusted to him, since a ship is ordained to something else as its end, viz. to navigation.” (Quotle.info)
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Provenance
What Aquinas actually wrote
Work
Summa Theologiae
Passage
Part I-II, Question 2, Article 5 (“Whether man’s happiness consists in any bodily good?”), “I answer that”
Translation
Fathers of the English Dominican Province (New Advent labels it the Second and Revised Edition, 1920)
Latin
“Unde gubernator non intendit, sicut ultimum finem, conservationem navis sibi commissae”
First, because, if a thing be ordained to another as to its end, its last end cannot consist in the preservation of its being. Hence a captain does not intend as a last end, the preservation of the ship entrusted to him, since a ship is ordained to something else as its end, viz. to navigation. Now just as the ship is entrusted to the captain that he may steer its course, so man is given over to his will and reason.
ST I-II, q. 2, a. 5
English Dominican translation. The passage never mentions a port, “forever,” or a captain’s “highest aim.” Those words belong only to the popular paraphrase.
In the English Dominican translation of Summa Theologiae I-II, q. 2, a. 5, Aquinas writes that “a captain does not intend as a last end, the preservation of the ship entrusted to him”. He uses the image to argue that happiness cannot consist in bodily goods. The article has no port (New Advent ↗).
The Latin original reads: “Unde gubernator non intendit, sicut ultimum finem, conservationem navis sibi commissae; eo quod navis ad aliud ordinatur sicut ad finem, scilicet ad navigandum” (Corpus Thomisticum ↗).
Quote sites carry the “keep it in port forever” wording with no question or article number. Goodreads cites no source (Goodreads ↗), and Philosophy News credits only “Summa Theologica” by title, in a “was” variant (Philosophy News ↗).
The line is not among the quotations on Wikiquote’s Thomas Aquinas page (Wikiquote ↗). A search also found no Quote Investigator entry for it, so no specialist has traced who first wrote the paraphrase.
The popular sentence has no identifiable author or first publication, so no copyright status is claimed for it. The genuine passage it paraphrases is from Aquinas’s 13th-century Latin. The English rendering quoted above is the Dominican Fathers’ translation, which New Advent ↗ labels the Second and Revised Edition, 1920.
Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.
Fact-check
Where the popular version goes wrong
The line is pinned on Aquinas almost everywhere, usually as a motto about taking risks. It is a loose retelling of one sentence in the Summa, with a new punchline added.
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The wordingThomas Aquinas, as popularly quoted Paraphrase
Aquinas says a captain’s last end is not the preservation of his ship, because a ship exists for navigation. He never says the captain would “keep it in port forever” (ST I-II q. 2 a. 5 ↗).
✕
The citation“Summa Theologica” with no reference Unsourced
Sites that name a source give only the title, with no part, question or article. Philosophy News is one example, and it prints “was” where others print “were” (Philosophy News ↗).
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A look-alike saying“A ship in harbor is safe, but that is not what ships are built for” Different quote
This is a separate saying, not a version of Aquinas. Quote Investigator credits it to John A. Shedd’s Salt from My Attic (1928). Its investigation does not mention Aquinas (Quote Investigator ↗).
✓What Aquinas actually wrote: “Hence a captain does not intend as a last end, the preservation of the ship entrusted to him, since a ship is ordained to something else as its end, viz. to navigation” (Summa Theologiae I-II, q. 2, a. 5 ↗).
Context
What the image meant to Aquinas
In the Summa, the captain is not a lesson about courage. It is a step in a proof about happiness. Aquinas argues that if a thing is ordered to something beyond itself, its last end cannot be its own preservation. A captain does not treat keeping the ship intact as his final goal, because the ship exists to sail. In the same way, he says, man is entrusted to his own will and reason. So man’s last end cannot be bodily goods or the mere preservation of his being.
The popular version keeps the logic but adds a vivid punchline, a ship kept in port forever, and turns a point about the purpose of human life into a motto against playing it safe. That is a fair reading of the spirit, but the sentence people quote is not his.
A ship is ordained to something else as its end, viz. to navigation.
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Filed under
More provenance-checked quotes on the same theme, each with its reuse status.
c. 1225–1274 · Dominican friar, theologian & philosopher
Thomas Aquinas was an Italian Dominican friar, born around 1225, probably at Roccasecca near Aquino. He died at Fossanova on 7 March 1274. His Summa Theologiae, written 1265–1274 and left unfinished, is the most influential work of scholastic theology. The captain-and-ship image comes from its treatise on happiness, where he argues that man’s last end cannot be merely the preservation of his own being.
For writers & researchers
Cite this
Genuine source of the idea
Thomas Aquinas, Summa Theologiae I-II, q. 2, a. 5, trans. Fathers of the English Dominican Province, 2nd rev. ed. (1920), New Advent, https://www.newadvent.org/summa/2002.htm. The popular wording (“keep it in port forever”) is a paraphrase not found in the text.
This verification page
Quotle.info. “Who really said ‘If the highest aim of a captain were to preserve his ship, he would keep it in port forever’?” Last verified 3 Nov 2026. https://quotle.info/who-said/if-the-highest-aim-of-a-captain-were-to-preserve-his-ship/