When Jesus tells John's people what to look for, it's not big, grandiose stuff. As concerns signs of the kingdom, Jesus points to people who couldn't see much, seeing more...people who couldn't climb out of bed in the morning, playing Ring Around the Rosie in the townsquare...Previously untouchable lepers kissing their wives and hugging their children....and the poor, hearing a good sermon for a change. And I suppose if you're blind, lame, poor or your skin used to be all scales and scabs, that's big time stuff. But can you build a kingdom on it?
Apparently, Jesus thinks you can. He doesn't care whether it's "big time stuff" or not. As concerns the kingdom, it breaks through in little ways. But it breaks through. As if to illustrate his point, he talks about a seed that nobody can see growing. But it's in there. I mean, it's already in there. You aren't going to see it come to maturity all at once. Like the hymn says, "First the blade, then the ear, then the full corn shall appear."
No, you may not see it. But neither are you going to be able to stop it. It's like that dandelion that finds a crack in the asphalt. Or creates a crack in the asphalt. Not only does it have presence, but there is an inevitability to its appearance.