The late Dutch professor Gilles Quispel stated that the five trees represent the five spiritual senses.
But why make it so difficult? Why can they not simply represent the five physical senses?
Give me the view of the blue glistering ocean, the sweet music of a bird's song, the smell of a rose, the taste of bittersweet dark chocolate or the touch of a lover and I am in heaven.

I admit it requires a certain amount of inner peace and stillness to enjoy the simple pleasures of life. If I am angry or simply a bit depressed that whole bar of chocolate has usually disappeared before I even notice it. And when I'm tired and stressed and really trying to get some sleep the sound of birds' chirping at four in the morning can just be that little bit too much to bear. But on those occasions that I do get to taste the true pleasures of life there is simply no room left for any of the lethal poisons of death and all its allies.