How does Shakespeare glorify true love in Sonnet 116?

Sonnet 116 claims that true love is not based on practicality, pragmatism, or any other material standard, but rather that true love exists beyond these concerns, beyond change ("alterations") and beyond time ("Love's not Time's fool"). Rather, true love is completely and eternally fixed ("an ever-fixed mark"), unmoving, and unaware of the material, physical world around it.

In lines 7 and 8, Shakespeare uses the metaphor of the star to make the important argument that while we can look at true love like we can observe a star in the sky ("his height be taken"), we cannot assign it a value (its "worth's unknown"). One of the points of this sonnet is to say that while humans have an innate sense that true love exists, our attempts to describe true love and explain it always come up short. Unlike true love, our lives are flexible, moveable, physical, and temporary, which means that we will never be able to describe the actual worth or experience of true love in words. For this reason, the poem does not, for the most part, describe what true love is; it describes what true love is not. The negative sentence structures begin in line 1 when the speaker says, "Let me not" admit that true love has faults. He proceeds to describe true love as not alterable, not bending, never shaken, and not "Time's fool." The one positive sentence in the poem—and, once again, the poem's central argument—occurs in lines 7 and 8:

It is the star to every wand'ring bark, / Whose worth's unknown, although his height be taken.

True love can only be described through a metaphor of something else that is beyond our human conceptions of space and time, a star. True love is not subject to the powerful forces of time, but we humans, with our "rosy lips and cheeks" that eventually fade, are affected by time. Therefore, it is difficult for us to explain true love, although we know it and can feel it, just as it is difficult for us to explain the nature of a star, though we know what a star is and can see it above us at night.

In Sonnet 116, the speaker glorifies true love by comparing its resilience to the common obstacles that love faces:  change, strife, and time.  The speaker argues that when life changes occur, true love does not get removed when all else around it starts to change.  Similarly when "tempests" look upon lovers, they who are truly in love weather the storms and deal with strife so that they can move past these situations into calmer times.  Finally, the speaker says that "Love's not Time's fool" which suggests that true love does not fade or disappear over the course of time--in fact, it may even get stronger and last until the end of Time.  In the closing couplet, the speaker puts his credibility on the line by saying that if he is wrong, then no person has ever loved and therefore do not know what love is.

How is love portrayed in Shakespeare's Sonnet 116?

Love is presented as the meeting and coming together "of two minds," rather than two bodies or something else. Love is much more mental than it is physical. Further, a true lover does not seek to change their loved one; whatever feeling that compels a person to try to alter another cannot rightfully be called love. Instead, love is an "ever-fixed mark," something steady and constant that cannot be shaken by any force, physical or otherwise. It provides a reliable light in the darkness to those who are lost or far away. Neither is love subject to the ravages of time, and, though beauty—"rosy lips and cheeks"—may fade, love itself will not decay or fade. It never wanes or lessens and remains faithful eternally. The speaker of the poem is so sure of this that he declares that, if he is mistaken, he has never written anything nor has any man ever loved at all.

People in the English Renaissance and earlier tended to see a major contrast between two different kinds of “love.” One kind of love was known as caritas (charity) and involved love of God and love of everything else as God would love. A wholly different kind of “love” (which was not true love at all) was called cupiditas (cupidity), or selfish desire.

William Shakespeare’s sonnet 116 (beginning “Let me not to the marriage of true minds”) is one of the most powerful celebrations of caritas in the English language.  The speaker begins by mentioning “the marriage of true minds” (1; emphasis added). This line immediately suggests that the love celebrated here is caritas, because love of another person’s mind, character, and soul characterized caritas, while mere desire for another person’s body characterized cupiditas. Another indication that the love celebrated in sonnet 131 is caritas appears when the speaker declares that

. . . love is not love

Which alters when it alteration finds . . . (2-3)

True love, in other words, is not affected by change, especially physical change in the beloved.  True love, like the love of God, is constant and immutable. It is dependable; it is long-lasting (even eternal); it is like the north star (7-8) in the sense that one can chart one’s path through life by relying on it. Cupiditas, in contrast, is wholly undependable and constantly altering. Deterioration in the physical attractiveness of the object of selfish desire almost always results in a loss of cupidinous “love” for that person. This is not the case with caritas, and indeed the love of two people who are truly in love with one another’s minds and souls is only likely to deepen and become richer with the passage of time.

The speaker of the poem makes all these ideas quite explicit when he asserts that true

Love’s not Time’s fool, though rosy lips and cheeks
Within his [that is, Time’s] bending sickle’s compass come . . . (9-10)

In other words, no matter how much the physical appearance of the beloved may fade over time, true love does not fade. Indeed, true love will last even until the end of time (11-12). In fact, the reference to “doom” in line 12 helps remind us of Judgment Day and thus again helps put the entire poem in a clearly Christian context. In the final two lines, the speaker declares his absolute confidence in the truth of the poem’s teachings. This highly memorable sonnet extols the virtues of genuinely virtuous love.