A rose is a rose is a rose

The sentence "Rose is a rose is a rose is a rose." was written by Gertrude Stein as part of the 1913 poem Sacred Emily, which appeared in the 1922 book Geography and Plays. In that poem, the first "Rose" is the name of a woman. Stein later used variations on the phrase in other writings, and "A rose is a rose is a rose" is probably her most famous quote, often interpreted as "things are what they are". In Stein's view, the sentence expresses the fact that simply using the name of a thing already invokes the imagery and emotions associated with it. As the quote diffused through her own writing, and the culture at large, Stein once remarked "Now listen! I’m no fool. I know that in daily life we don’t go around saying 'is a … is a … is a …' Yes, I’m no fool; but I think that in that line the rose is red for the first time in English poetry for a hundred years." (Four in America)
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Meaning
The notion that when all is said and done, a thing is what it is.
Origin
From Gertrude Stein's Sacred Emily.