I've had Miłosz' Collected poems sitting on my shelf for decades and just fished that out this evening. He was writing this poem in the horrendous years of Nazi occupation in Warsaw. It's part of a set of very simple, nostalgic little lyrics called "The World", full of memories if sunny childhood. The poets name, Miłosz, means "love" in Polish.
I was going to switch out the "he" for a more gender-neutral "they" (since it is a translation) but it gets complicated then in the second stanza - so I've left it as is...
Love means to learn to look at yourself
The way one looks at distant things
For you are only one thing among many.
And whoever sees that way heals his heart, Without knowing it, from various ills --
A bird and a tree say to him: Friend.
Then he wants to use himself and things
So that they stand in the glow of ripeness.
It doesn't matter whether he knows what he serves:
Who serves best doesn't always understand.