The Pharisees totally missed the point. There was the guy with the withered hand. They had no compassion for him. They just wanted to see if Jesus would break their own rules. This broke Jesus's heart! Jesus heals the guy anyway, and the Pharisees left figuring out how to get Jesus killed because He didn't act the way they wanted Him too.
How often do we humans do this same thing? We harden our hearts toward others, toward Believers, toward non-believers, and watch to see them act how we expect them too. We give them no chance to be who God created them to be. We assume bad behavior. And no matter what they do we interpret it according to our own callousness and they cannot win with us.
In the next chapter of Mark Jesus talks about the sower and the seeds. Read it if you have time. He gives two things that will stop the Word growing in us. First is hardness of heart. Second is worries and the desire for riches (and the things of this world). Worries and lusting after the stuff of this world are really two sides of the same coin.
And both of these conditions we control -- we choose to harden our hearts. We choose to worry and lust after stuff.
God does the growing but we can stop the growth if we cut ourselves off from the source, if we grab onto it and squeeze the life out of it. Nothing is uglier than a stunted tree that has no leaves or fruit. It just stands there naked and giving nothing to its world -- not even a beauty. It may draw the eye but just because of it being so odd.