Those lines that I before have writ do lie,
Even those that said I could not love you dearer:
Yet then my judgement knew no reason why
My most full flame should afterwards burn clearer.
But reckoning Time, whose million’d accidents
Creep in ’twixt vows, and change decrees of kings,
Tan sacred beauty, blunt the sharp’st intents,
Divert strong minds to the course of altering things;
Alas! why fearing of Time’s tyranny,
Might I not then say, ‘Now I love you best,’
When I was certain o’er incertainty,
Crowning the present, doubting of the rest?
Love is a babe, then might I not say so,
To give full growth to that which still doth grow?
In plain English
I've written poems before that claimed I couldn't love you more deeply than I already did — and those poems were false. At the time, I had no way of knowing that my love would only intensify. But Time is ruthless: it works constant damage between one moment and the next, changing even a king's decree, fading beauty, weakening resolve, pulling strong minds toward whatever changes next.
So here's my defense: knowing how brutal Time is, wasn't I reasonable to say 'I love you most' in that moment, when I was certain of what I felt then, rather than worried about an uncertain future? I was crowning the present while doubting everything else. Love is still growing, still being born — so wasn't it fair to name it as I found it?
The speaker admits his earlier poems overstated finality. He reframes this not as dishonesty but as wisdom: you can't promise what Time will do, so you name what's true right now.