Taste
Taste is a major theme in the poem. In keeping with his desire to be direct, Williams ends the poem with a strong and impactful moment of the speaker remembering the taste of the plums. With a few small details, the speaker is able to immediately conjure a clear sensory picture of consuming the plums. This moment occurs as part of the apology, but also offers a kind of summary of what it was that drew him to the plums in the first place. Taste holds a central place in the poem, as Williams frames the memory of the taste as being just as salient as the taste itself. By depicting it so powerfully in the poem (and using it as a partial excuse for eating someone else's food), he reveals the way in which taste lingers in the mind, an unforgettable trace of the plum. Its cool sweetness quietly represents so many commonplace pleasures.
Guilt
One of the poem's most obvious themes is guilt. While the speaker's supposed crime (the consumption of the plums) is of relatively small consequence, the guilt he feels is very apparent. Aware that his wife was saving these particular plums, the speaker asks for her forgiveness. While this request feels like something of an overstatement, the speaker's guilt seems directly related to his enjoyment of the plums themselves. In briefly reminiscing about their taste, he appears as guilty about eating them as he is about so thoroughly enjoying them. There is a subtle implication of temptation. Guilt, in the speaker's conception here, is tied to the failure of self-control.
Communication
One of the poem's main themes is communication. While framed in a somewhat plain and casual tone, the poem is a direct address from the speaker to his wife. He openly acknowledges his error in eating the plums, while offering an explanation for having done so. Communication is important to the poem in that the speaker is trying to be direct both about his guilt regarding his actions and his experience of enjoying the plums. In ending the poem with his visceral sensory recollection of the taste and temperature of the plums, he succeeds in conveying to his wife that while he is sorry, the plums were very difficult to turn away from.
