The theme of day 4 is bliss.
What is the definition of bliss? From a dictionary:
1. perfect happiness; serene joy
2. (Theology) the ecstatic joy of heaven
[Old English blīths; related to blīthe blithe, Old Saxon blīdsea bliss]
For me, bliss is being out in nature. I also like the second definition and I think that nature does provide a glimps of heaven!