Heaven - pie in the sky?

In the book "The problem of pain" C.S.Lewis suggests we are sometimes
reticent to talk about heaven as we are quickly accused of 'escapism'.
On the other side of the scale 'heaven' can also be understood as a
bribe that gets us working harder in the now. The third way is the
better way. The pure in motive actually want to meet with God. There
lives are set in knowing more and becoming more like God whom they
love. There is nothing mercenary or escapist about this desire and it
is this Way that builds hearts and nations.