The purpose of Shakespeare's sonnet cycle is not only to praise the beauty of the young man. The purpose is also to express the great love that the speaker feels for this young man. The greatest poetry throughout time has always dealt with love in one form or another. And one of the finest poems that expresses the meaning of love is "Sonnet 116."
For the most part, this sonnet defines love. In terms of its structure, the shift in the poem comes between the third quatrain and the couplet. However, all fourteen lines are used to express the depth and significance of a true and heartfelt love.
In the first quatrain, the speaker suggests that there should be no obstacles, problems, or "impediments" in a relationship where both parties are "true." The word true here implies both fidelity and honesty. It also hints at a kind of purity in the relationship. The speaker is not talking about a conventional marriage. He is talking about a "marriage of minds," a spiritual connection between the souls of the two individuals. This is a higher love, and such a love does not suffer or end when some obstacle gets in the way. The word alteration (in line 3) also suggests an obstacle or setback that may occur in the relationship. Even though problems or alterations may occur at times in the relationship, the nature of the relationship itself does not alter. Both parties remain true. Both still love one another. The speaker repeats the idea a third time (in line 4) with