Sonnet 7 in the 1609 Quarto.

Scholars are uncertain whether the sonnets were originally written for a woman or a man, though most agree that a man is more likely. It’s part of the Fair Youth sequence of sonnets–numbers 1–126–which was dedicated to a “Mr. W.H.” Popular candidates for the identity of W.H. include Henry Wriothesley, 3rd Earl of Southampton, and William Herbert, 3rd Earl of Pembroke, both of whom were patrons of Shakespeare.

The gender of the person to whom the sonnet is addressed is irrelevant to our understanding of the meaning and the quality of the composition. However, at the time many sonneteers wrote as an intellectual exercise intended for friends and other writers who were also producing sonnets, though is believed not to be the case with Shakespeare’s sonnet sequences.

Shakespeare continues his preoccupation in the sonnet sequence with urging the young man to procreate in order to preserve his beauty for posterity. The poet frames this in terms of the rising and setting sun, and youth and age. This is a theme that Shakespeare visits again and again in the sequence, most notably in the admired Sonnet 73.

In the sunset of his days the youth will no longer be surrounded by admirers. Unless he has children to carry on the line and reflect his former beauty, he will disappear into the depths of time.

The rising sun is admired. It climbs higher to reach its zenith, but moves downwards towards evening. Admiring looks are averted, and, like ‘unregarded age in corners thrown’, it is ignored. Other beautiful young men will take precedence. So it is crucial that the young man should “get (beget) a son”.

ABOUT SONNETS
A sonnet is a poem which expresses a thought or idea and develops it, often cleverly and wittily.

The sonnet genre is often, although not always, about ideals or hypothetical situations. It reaches back to the Medieval Romances, where a woman is loved and idealised by a worshipping admirer. For example, Sir Philip Sydney in the Astrophil and Stella sonnet sequence wrote in this mode. Poems were circulated within groups of educated intellectuals and they did not necessarily reflect the poet’s true emotions, but were a form of intellectual showing-off. This may not have been true of all; it is a matter of academic debate today. It is debated as to whether Shakespeare’s sonnets were autobiographical.
BBC Podcast, Melvyn Bragg, “In Our Time” Shakespeare’s Sonnets

BBC Radio 4 - In Our Time, Shakespeare's Sonnets — BBC

Melvyn Bragg and guests discuss some of the greatest and most challenging poems in English

Sonnets are made up of fourteen lines, each being ten syllables long. Its rhymes are arranged according to one of the following schemes:

• Italian, where eight lines consisting of two quatrains make up the first section of the sonnet, called an octave. This section will explore a problem or an idea. It is followed by the next section of six lines called a sestet, that forms the ‘answer’ or a counter-view. This style of sonnet is also sometimes called a Petrarchan sonnet.

• English, which comprises three quatrains, making twelve lines in total, followed by a rhyming couplet. They too explore an idea. The ‘answer’ or resolution comes in the final couplet. Shakespeare’s sonnets follow this pattern. Edmund Spenser’s sonnets are a variant.

At the break in the sonnet — in Italian after the first eight lines, in English after twelve lines — there is a ‘turn’ or volta, after which there will be a change or new perspective on the preceding idea.

Language
The metre is iambic pentameter, that is five pairs of stressed and unstressed syllables to the line. The effect is elegant and rhythmic, and conveys an impression of dignity and seriousness. Shakespeare’s sonnets follow this pattern.

In sonnet 7 an analogy is drawn between the rising and setting sun, and the imperative for the young man to beget a son before his beauty fades and is lost to posterity.

Rhyme Scheme
The rhyming pattern comprises three sets of four lines, forming quatrains, followed by a closed rhyming couplet.

In Sonnet 7 it forms ABAB, CDCD, EFEF, GG. This is typical of Shakespeare’s compositions.

See Don Paterson – Reading Shakespeare’s Sonnets, Faber & Faber, 2012
Helen Vendler The Art of Shakespeare’s Sonnets Harvard University Press
Shakespeare’s Sonnets with Three Hundred Years of Commentary, Associated University Press 2007
BBC Podcast, Melvyn Bragg, “In Our Time” Shakespeare’s Sonnets