Grace, God's presence within you, is like seed - a vital, growing seed that is destined one day to break forth full-grown.
God has given himself to you, but in a hidden way. For the time being, you seek him even as you possess him. But the time will come when your seeking will be over. You will then see and possess God completely. This has been revealed.
In his first letter Saint John tells us," Beloved, we are God's children now; it does not yet appear what we shall be, but we know that when he appears we shall be like him, for we shall see him as he is" (1 Jn 3:2)
And in his first letter to the Corinthians, Saint Paul says,"For now we see in a mirror dimly, but then face to face. Now I know in part; then I sahll understand fully, even as I have been fully understood" (1 Cor 13:12)
This is heaven : direct face-to-face vision of God as he is - Father, Son and Spirit; total and perfect union with God, an ecstasy of fulfillment beyond human imagining; the 'now' of eternity in which everything is ever new, fresh, and present ot you; the warm flood of joy in the company of Jesus, his Mother, and all the people you have ever known and loved; a total absence of pain, regret, bad memories; the perfect enjoyment of all your powers of mind and (after the resurrection on Judgement Day) of body.
This is heaven. That is to say, this is a pale, human indication of what God has promised to those who love him, of what Christ has gained for us by his death and Resurrection.