"We were very tired, we were very merry—
We had gone back and forth all night on the ferry."
This is quite clearly a very significant quote in the poem because it is repeated as the opening lines of all three stanzas. This is an example of a poetic device called anaphora, which is a term for the repetition of words or phrases at the beginning of a line. The point of the repetition in poetry is just like that in conversation: to provide emphasis. By the time the poem is over, the reader knows beyond any question that this is a story about two people who had a great time with each other and that left them exhausted in the very best way. The title of this poem is a Spanish word that means "memory" and that is exactly what this verse is all about. It is a warm memory of an exciting event in the speaker's youth.
"And you ate an apple, and I ate a pear,
From a dozen of each we had bought somewhere"
The happy memory of this event is not built upon any amazing things which happened. The poem is filled with references to enjoyment of the simple things in life. This quote is an example. The couple buy a dozen apples and a dozen pears. This is not a memory about eating steak and drinking champagne. Adding to the enjoyment of what one has is that it winds up that they don't even eat all the fruit. They will wind up giving a poor old woman the surplus of leftover fruit for which she will express gratitude. This further cements the idea that enjoyment of life is not dependent on abundance or wealth or even external entertainment. It is a celebration of being with another person you enjoy.
"And we gave her all our money but our subway fares."
The final line of the poem encapsulates the thematic force driving the narrative. The old woman to whom they have given what remains of their supply of fruit also enjoys what little money they have when they give it to her. That they are riding the subway indicates that they are not wealthy enough to enjoy private transportation. That they do not care to keep any more than enough to ensure they can get home indicates that greed is not their driving motivation. Their time together has tired them out, but it has also left them merry. So merry that they seem to be infused with the spirit Christmas giving even though there is nothing to suggest this takes place during the holidays. It is truly a celebration of appreciating the simple enjoyments of life.