God cries out that the kingdom of heaven is for sale. The glorious bliss of this kingdom surpasses the power of mortal eye to see, mortal ear to hear, mortal heart to conceive. If anyone asks the price that must be paid, the answer is: The One who wishes to bestow a kingdom in heaven has no need of earthly payment. No one can give God anything he does not possess, because everything belongs to him. Yet he does not give such a precious gift entirely gratis, for he will not give it to anyone who lacks love. After all, people do not give away what they hold dear to those without appreciation. So since God has no need of your possessions but must not bestow such a precious gift on anyone who disdains to value it, love is the one thing he asks for; without this he cannot give it.
Give love, then, and receive the kingdom: love and it is yours.
To reign in heaven simply means exercising a single power with God and all the holy angels and saints through being so united with them in love as to want only what they want.
Love God more than yourself, then, and already you will begin to have what you desire to possess fully in heaven. Be at one with God and with other men and women—so long as they are not at variance with God—and already you will begin to reign with God and all the saints.
The desires of God and all the saints will be the same as yours in heaven, if your desires now are the same as those of God and other people. So, if you want to be a king in heaven, love God and other people as you should and then you will deserve to become what you desire. But you cannot have this perfect love unless you empty your heart of every other love.
That is why those who fill their hearts with love of God and neighbor desire nothing but the will of God or that of some fellow human being—provided this is not contrary to God.
That is why they devote themselves to prayer, spiritual conversations, and reflection, for it is a joy to them to long for God and to speak, hear, and think about him whom they dearly love.
That is why they rejoice with those who rejoice, weep with those who weep, show compassion to those in distress, and give to the needy, since they love others as themselves.
Hence too their contempt for riches, power, pleasure, honor, and praise. Those who love these things frequently offend against God and their neighbor—”for the whole law and the prophets depend on these two commandments.”
So those who wish to possess the fullness of that love which is the price of the kingdom of heaven should love contempt, poverty, toil, and subjection, as do the saints.
St Anselm of Canterbury