Summary
Sonnet 138 describes a complicated relationship between the speaker and his lover. Their relationship is based on mutual deception. The lover swears that she is faithful to the speaker, but he knows that this a lie. Still, he does not say anything. Similarly, the speaker likes to present himself as younger than he is because he is self-conscious about his age. His lover is very much aware of how old the speaker is yet she humors him so that he can feel better about himself. In fact, he intentionally pretends to believe his lover’s lies about not cheating on him because acting naive and inexperienced in love helps him present himself as younger than he actually is.
Why do the speaker and his lover lie to each other and then pretend to believe these lies? The sonnet argues that the best thing about love is “seeming trust.” This can mean both “appearing to trust” and “trusting in appearances.” According to the poem, this kind of lie is actually better than the truth because the lover does not want to admit that she is unfaithful; similarly, the speaker does not want to admit that he is old. The poem ends with a couplet tying all of these themes together: “Therefore I lie with her and she with me, / And in our faults by lies we flattered be.” In other words, telling each other lies allows them to feel better about themselves. The couplet plays with the double meaning of “lie:” both telling an untruth and lying down or sleeping together. The poem shows how the romantic relationship between the speaker and his lover depends on lies. Paradoxically, lies are what bring them together and make their love possible.
Analysis
The first stanza opens with a paradox: “When my love swears that she is made of truth, / I do believe her, though I know she lies.” The speaker is aware that his lover is lying but he believes what she says anyway. The sonnet is based on this paradox: sometimes the best way to respond to a lie is to believe it. In the specific case of the poem, the speaker’s lover is lying about being faithful to him. “Made of truth” can mean both "completely truthful" and “maid of truth” (”maid” being the word used in Shakespeare’s time for a young woman or virgin). The speaker knows very well that his lover is neither a virgin nor truthful. So why does he choose to believe her? The answer is in the last two lines of the first stanza: “That she might think me some untutored youth, / Unlearnèd in the world’s false subtleties.” In other words, he believes her lies because it allows him to pretend to be younger than he is: only an inexperienced young man would be so ignorant about how the world really works. Acting gullible lets him pretend to be young again.
The second stanza continues with this theme of age. The line “Thus vainly thinking that she thinks me young” shows that the speaker chooses to believe his lover’s lies because it flatters his vanity. It also shows exactly how complicated this relationship is: the speaker is only self-confident about his age when he thinks about what his lover is thinking. She only pretends to think he is young in order to make him feel better. The reality is this his “days are the past the best.” This line shows that he does not even admit to himself that he is old. Instead, he uses a euphemism. In the second half of this stanza, the speaker says: “Simply I credit her false-speaking tongue: / On both sides thus is simple truth suppressed.” In other words, he chooses to believe the lies coming out of his lover’s mouth just as she chooses to believe his lies. The word “simply” can both mean “fully,” and "like a simpleton” or an inexperienced idiot. “Credit” means “believe,” but because it is also a financial term it suggests these lies are like a transaction made to buy their peace of mind. Yet the result is that “on both sides” (her lies about being faithful, his lies about being young) the obvious truth is swept under the rug.
Stanza three begins with two questions: “But wherefore says she not she is unjust? / And wherefore say not I that I am old?” In other words, why does she not just say that she is dishonest and cheating on him, and why does he not just admit that he is old? The sonnet’s answer is a complicated one: “Oh, love’s best habit is in seeming trust.” In addition to its most common meaning, “habit” can also mean “clothing.” Clothing is used both to cover up bodies and to disguise them. In this sense, the best thing for lovers to do (and the best way for them to disguise the truth) is to pretend to believe each other. In this way, they choose to put their trust in how things appear, or how they would like them to appear. The final line of the stanza gives an example of this: “age in love loves not to have years told.” In other words, old lovers prefer not to be reminded of their age. For this reason, “seeming trust”—trust in what one is shown—is better than actual honesty because it allows the lovers to believe what they want.
The final couplet shows a change in the argument (in sonnets, this is called the “volta” or “turn”). The speaker now openly admits what is happening in this complex relationship: “Therefore I lie with her and she with me, / And in our faults by lies we flattered be.” The first line of the couplet draws a link between lying to each other and lying down together (sleeping together). In the context of the sonnet, this double entendre (the use of a figure of speech or phrase that has two meanings, one literal and the other sexually suggestive) suggests that the lovers are only able to sleep together because they are untruthful together. The lies are the foundation of their relationship. It allows them to be “flattered” by their “faults” (lying and cheating as well as physical imperfections that come from old age). By lying, they make themselves and each other feel better. It is also worth noting that the final line of the poem is the first time we see the pronoun “we.” Before this point, it is only “I” and “she.” As the lovers “lie together” in the couplet, they are also united grammatically in the same sentence.