Shakespeare’s speaker here is defending himself against an unspoken accusation: that he worships his beloved too much, turning love into a kind of idolatry. He insists this isn’t so. His poems and praises aren’t scattered among many false gods — they’re all directed to one person, and that person has remained wonderfully constant, day after day. Because the beloved’s goodness doesn’t waver, the speaker’s verse doesn’t need to describe change or distraction. He confesses his entire theme boils down to three words: “fair, kind, and true.” Even though he plays with those words in different ways, the core never shifts. The closing couplet lands the real point with quiet pride: those three qualities have often existed separately in people before, but never, until now, have they lived together so perfectly in one human being. The mood is earnest and tender, not grandiose — a love that feels secure, almost relieved, to have found something so complete.
Sonnet 105: Let not my love be call'd idolatry — Summary
Let not my love be call'd idolatry, Nor my beloved as an idol show, Since all alike my songs and praises be To one, of one, still such, and ever so. Kind is my love to-day, to-morrow kind, Still constant in a wondrous excellence; Therefore my verse to constancy confin'd, One thing expressing, leaves out difference. 'Fair, kind, and true,' is all my argument, 'Fair, kind, and true,' varying to other words; And in this change is my invention spent, Three themes in one, which wondrous scope affords. Fair, kind, and true, have often liv'd alone, Which three till now, never kept seat in one.