Time flies like an arrow; fruit flies like a banana
"Time flies like an arrow; fruit flies like a banana" is a humorous saying that is used in linguistics as an example of a garden path sentence or syntactic ambiguity, and in word play as an example of punning, double entendre, and antanaclasis.
The expression is based on the proverb: "Time flies", a translation of the Latin Tempus fugit. This translation is misleading to the modern English speaker, because the Latin fugit did not mean fly in the sense of aviation, but in the sense of flee (cf. "fugitive"); in modern English to say "fly" when meaning "flee" would be unusual. However, this does not seriously affect the perceived intention of the metaphor in practice.
An early example of a pun with the expression "Time flies" may be found in a 1930 issue of Boys' Life:
In that form it had already appeared in discussions on linguistics and later in discussions on the feasibility of computer-based linguistic work, but by the mid-1960s the elaboration "time flies like an arrow" appeared in related contexts as an example of syntactic ambiguity. The saying is sometimes attributed to Groucho Marx, but according to The Yale Book of Quotations there is no reason to believe Groucho actually said this. Instead, it traces the quote to a 1982 post on the Usenet group net.jokes, which reads:
Seen on a bathroom wall:
Time flies like an arrow.
Fruit flies like a banana.
However, the juxtaposition of the phrases "time flies like an arrow" and "fruit flies like a banana" appears already in the 1960s as an example of the problems in having computers understand natural language. An early appearance in print, in slightly modified form, is from 1965:
"Time flies like an arrow" may seem fairly straightforward to us, but a machine sees a number of other possibilities, for example "Time the speed of flies as quickly as you can" ("time" being interpreted as a verb rather than a noun) and "Certain flies enjoy an arrow" ("time" being interpreted as an adjective, and "like" being interpreted as a verb). The machine could be instructed to rule out these particular offbeat parsings, but how would it handle the sentence, "Fruit flies like bananas"?
A more elaborate example involving bananas appeared in Scientific American in September 1966, a single-topic issue on information and computing, in an article on "The Uses of Computing in Science" by Anthony G. Oettinger. The material was published in book form shortly afterwards. This prompted the following response:
- Time Flies Like an Arrow
- An Ode to Oettinger
- Now, thin fruit flies like thunderstorms
- And thin farm boys like farm girls narrow;
- And tax firm men like fat tax forms -
- But time flies like an arrow.
- When tax forms tax all firm men’s souls,
- While farm girls slim their boyfriends’ flanks;
- That’s when the murd’rous thunder rolls -
- And thins the fruit flies ranks.
- Like tossed bananas in the skies,
- The thin fruit flies like common yarrow;
- Then's the time to time the time flies -
- Like the time flies like an arrow.
- Edison B. Schroeder 1966
The verse is popular as a specimen of didactic humor trading on syntactic ambiguity. Like the poem The Chaos, by Gerard Nolst Trenité, its themes are popular among practitioners and students in fields such as natural language processing and linguistics.
Use in linguistics
It is also used as an example of punning. The wordplay is based on the distinct meanings of the two occurrences of the word flies (the verb "travel through the air" and the noun for certain insects), and of the word like (the preposition "similarly to" and the verb "enjoy"). For example, the second clause can be read as "fruit travels through the air similar to a banana" or as "certain insects enjoy a banana".
This is an example of a garden-path sentence, a phrase that the reader or listener normally begins to parse according to one grammatical structure, and is then forced to back up and reparse when the sentence ends in an unexpected way.
Analysis of the basic ambiguities
"Time flies like an arrow," is an English phrase often used to illustrate syntactic ambiguity. In this connection the sentence is often seen as part of the elaboration: "Time flies like an arrow; fruit flies like a banana".
Contemporary English speakers unambiguously understand the sentence to mean "As a generalisation, time passes in the same way that an arrow generally flies (i.e. quickly)" (as in the common metaphor time goes by quickly). However, the matter is more difficult in the formal interpretation of natural language; formally the sentence is logically ambiguous and alternatively could be interpreted as meaning for example:
- (as an imperative) measure the speed of flying insects like you would measure that of an arrow - i.e. (You should) time flies as you would (time) an arrow
- (imperative) measure the speed of flying insects like an arrow would - i.e. (You should) time flies by the same method that an arrow would (time them)
- (imperative) very quickly measure the speed of flying insects - i.e. (You should) time flies as quickly as an arrow would (be or move)
- (imperative) measure the speed of flying insects that are like arrows - i.e. (You should) time (those) flies (that are) like an arrow
- (declarative, i.e. neutrally stating a proposition) all of a type of flying insect, "time-flies," collectively enjoy a single arrow (compare Fruit flies like a banana)
- (declarative) each of a type of flying insect, "time-flies," individually enjoys a different arrow (similar comparison applies)
- (declarative) each of a type of flying insect, "time-flies," individually enjoys an occasional arrow when there is an opportunity (compare: "He prefers beer, but I like a martini")
- (declarative) the common metaphor "time," moves in a way an arrow would (which, depending on the context of the phrase may mean "moves in a straight line", "moves by parabola", "its movement depends on the wind", etc.)
- (declarative) a copy of the magazine Time, when thrown, moves in a similar manner to that of an arrow.
- List of linguistic example sentences
- Sentence processing
- Syntactic ambiguity
- Boys' Life (Boy Scouts of America, Inc): 48. February 1930. ISSN 0006-8608. "The official youth magazine for the Boy Scouts of America"
- Rigney, Francis J. (February 1930). "Think and Grin". Boys' Life. Boy Scouts of America. p. 48.
- Fred R. Shapiro, ed. (2006). The Yale Book of Quotations. Yale University Press. p. 498. ISBN 978-0-300-10798-2.
- Gilbert Burck (1965). The computer age and its potential for management. Harper & Row. p. 62.
- Gerard Piel, Dennis Flanagan, et al.(pub & eds); Information; W.H.Freeman, 1966. Lib. of Congress No. 66-29386
- Scientific American, November 1966, p. 12, correspondence column
- Jurafsky, Daniel & Martin, James H. Speech and Language Processing. Pub. Pearson Prentice Hall 2008. ISBN 978-0131873216
- Marc de Mey(1982), The cognitive paradigm: an integrated understanding of scientific development D. Reidel (1992), University of Chicago Press (1992).