Beyond what I have heard and seen, there are things which I can imagine: I can imagine a world in which there never would be pain, nor disease, nor death; I can imagine a world wherein every man would live in a castle, and in that commonwealth of castles there would be a due order of justice without complaint or anxiety; I can imagine a world in which the winter would never come, and in which the flowers would never fade, and the sun would never set; I can imagine a world in which there would always be a peace and quiet without idleness, a profound knowledge of things without research, a constant enjoyment without satiety; I can imagine a world which would eliminate all the evils and diseases and worries of life, and combine all of its best joys and happiness, and I wonder if all the happiness of heaven would be like the happiness of earth which I can imagine. . . 

Will eternity be anything like what I have seen, or what I have heard, or what I can imagine? No, eternity will be nothing like anything I have seen, heard, or imagined. Listen to the voice of God: “Eye hath not seen, nor ear heard, neither hath it entered into the heart of man what things God hath prepared for them that love Him.” 

If the timeless so much surpasses time that there can be found no parallel for it, then I begin to understand the great mystery of the shape of the human heart. The human heart is not shaped like a valentine heart, perfect and regular in contour; it is slightly irregular in shape as if a small piece of it were missing out of its side. That missing part may very well symbolize a piece that a spear tore out of the universal heart of humanity on the Cross, but it probably symbolizes something more. It may very well mean that when God created each human heart, He kept a small sample of it in heaven, and sent the rest of it into the world of time where it would each day learn the lesson that it could never be really happy, never be really wholly in love, and never be really wholehearted until it went back again to the timeless to recover the sample which God had kept for it for all eternity.

Fulton J Sheen 'Go to Heaven: A Spiritual Road Map to Eternity'