How does structure affect the meaning of a sonnet, using ‘Sonnet 54’ by William Shakespeare as an example?

A Shakespearean sonnet is broken down into three quatrains and a rhyming couplet. The first two quatrains are grouped together and called an octave. The last quatrain and the rhyming couplet are grouped together and called a sestet. Knowing the different sections of a Shakespearean sonnet can be extremely helpful in evaluating the meaning. The octave usually introduces an issue with the sestet coming to a conclusion about it. The first quatrain typically opens the topic. The second develops it. The third provides a change. And the concluding couplet summarises the message. In ‘Sonnet 54’ Shakespeare introduces the theme of the sonnet: truth. He develops this through the extended metaphor of the rose in the first and second quatrain. While in the first he focuses on the real rose and the truth which it possesses, making it seemingly more virtuous, in the second he presents the ‘canker-blooms’ which are described as equally beautiful. It is in the third quatrain where he reveals the difference between the real rose and the copy one. Real roses make “sweetest odours” and perfume when they die. These scents are a metaphor for truth. While the copy roses ‘die to themselves’ without making such odours. This revelation shows that it is the real rose’s truth that sets it apart, while the “canker-blooms” can only mimic the real rose’s appearance it cannot produce the scent. The rhyming couplet beautifully summarises the message of the sonnet, linking the metaphor to the “youth”. The direct address promises the ‘youth’ that when their beauty fades, the sonnet will ‘distil’ their truth, their essence. The couplet sums up the sonnets message: that beauty is transient and only truth has real lasting value and can be retained. O how much more doth beauty beauteous seem, By that sweet ornament which truth doth give! The rose looks fair, but fairer we it deem For that sweet odour which doth in it live. The canker-blooms have full as deep a dye As the perfumed tincture of the roses, Hang on such thorns and play as wantonly When summer's breath their masked buds discloses: But, for their virtue only is their show, They live unwoo'd and unrespected fade, Die to themselves. Sweet roses do not so; Of their sweet deaths are sweetest odours made: And so of you, beauteous and lovely youth, When that shall fade, my verse distills your truth.