Sonnet 30

What's he saying?
"When to the sessions of sweet silent thought / I summon up remembrance of things past,"
When I am in a pensive state and recall my memories of past things,

"I sigh the lack of many a thing I sought / And with old woes new wail my dear time's waste:"
I regret that I did not achieve many things I tried to get, and with old regrets renewed I now grieve over having wasted my precious time:
"Then can I drown an eye, unused to flow / For precious friends hid in death's dateless night,"
Then I can cry, being unaccustomed to crying, over dear friends who have died,
"And weep afresh love's long since cancell'd woe / And moan the expense of many a vanish'd sight:"
And weep again over former loves that I put behind me long ago, and cry over the pain of many faded memories:
"Then can I grieve at grievances foregone / And heavily from woe to woe tell o'er"
Then I can grieve over past griefs and recount each sadness with a heavy heart,
"The sad account of fore-bemoaned moan / Which I new pay as if not paid before."
The sad remembrance of things I have grieved over already, which I now grieve over anew as though I never did before.
"But if the while I think on thee, dear friend / All losses are restored and sorrows end."
But as soon as I think of you, my dear friend, all those wounds are healed, and my sorrows come to an end.
Why is he saying it?
Sonnet 30 is at the center of a sequence of sonnets dealing with the narrator's growing attachment to the fair lord and the narrator's paralyzing inability to function without him. The sonnet begins with the image of the poet drifting off into the "remembrance of things past" - painful memories, we soon learn, that the poet has already lamented but now must lament anew. The fair lord enters the scene only in the sonnet's closing couplet, where he is presented as a panacea for the poet's emotional distress.
Closely mirroring the message of sonnet 29, here Shakespeare cleverly heightens the expression of his overwhelming anxiety by belaboring the theme of emotional dependence. Whereas in sonnet 29 he quits his whining after the second quatrain, in sonnet 30 three full quatrains are devoted to the narrator's grief, suggesting that his dependence on the fair lord is increasing. Meanwhile sonnet 30's closing couplet reiterates lines 9-14 of sonnet 29 in compact form, emphasizing that the fair lord is a necessity for the poet's emotional well-being: the fair lord is the only thing that can bring the poet happiness.
This pinnacle of the poet's plaintive state is beautifully conveyed through an artful use of repetition and internal rhyme. Beyond the obvious alliteration of "sessions of sweet silent thought," note the "-nce" assonance of "remembrance" and "grievances," to which may be added "since" and "cancell'd"; the correspondence of "sigh," "sought," and "sight"; and the rhyme in "foregone," "fore-bemoaned," "before," and "restored." It is as though the poet wishes to hammer in his hardship with the repetitive droning of his troubled soul.
Beyond its poetics, sonnet 30 also provides some prime examples of the poet's recurring tendency to describe his relationship with the fair lord in financial terms. The opening lines of the sonnet remind us of being called to court (cf. "court sessions" and "summon a witness"). This is followed by a slew of money-related terms, including "expense," "grievances," "account," "paid," and "losses." The phrase "tell o'er" in line 10 is an accounting expression (cf. the modern bank teller) and conjures up an image of the narrator reconciling a balance sheet of his former woes and likening them to debts that he can never pay off in full. The only cure for his financial hardship is the fair lord's patronage - perhaps something to be taken literally, suggesting that the fair lord is in fact the poet's real-world financial benefactor.