And writers say, as the most forward bud
Is eaten by the canker ere it blow,
Even so by love the young and tender wit
Is turn'd to folly, blasting in the bud,
Losing his verdure even in the prime,
And all the fair effects of future hopes.
They're talking about things of which they don't have the slightest understanding, anyway. It's only because of their stupidity that they're able to be so sure of themselves.