If the Kingdom of Heaven is hidden in our hearts, then it ought to pervade our whole lives.
I have seen an untidy woman, and an untidy home, perfectly transformed by the love of God, and her desire to please Him.
A year or two ago, I knew a woman who had become rather fond of drink. All at once she found that if she wanted to enter into "the Kingdom of Heaven," that temptation must be left off. So she told the Lord Jesus all about it, and then she left it off in the strength which He gave her; and she said to me: "I have never taken any since!"
So she found, like many others whom I have known, that when "the Kingdom of Heaven" takes possession of our hearts, our whole nature becomes changed, and we try to live to God's glory!
In the same chapter in Matthew, the thirteenth, that has in it the Parable about the leaven, our Lord gives us another picture of "the Kingdom of Heaven."
He describes a man who was digging in a field; who came by chance upon a great treasure.
The man hastily covered up the ground, and went to the owner of the field, and asked him to let him buy the whole field.
The price was very high, but the man thought of the treasure, and he did not hesitate. He went back, and sold all that he had, and came and bought the field. He did not grudge it, for the treasure was worth everything he possessed!
Then our Lord tells us of another man.
He was a merchant; and he travelled to far-off countries seeking beautiful pearls.