What does the line, "What man has made of man," mean in "Lines Written in Early Spring"?

This line is found in the following stanza:

To her fair works did Nature link
The human soul that through me ran;
And much it grieved my heart to think
What man has made of man.

The complete line of thought is that Nature (personified) has made the speaker aware of her beauties. By doing so, the speaker feels a both a connection with Nature and a unity with mankind. This oneness makes him keenly aware of the contrast in the way Nature’s “fair works” encourage man, yet mankind is so destructive to itself. Man initiates war on mankind. Man deprives its members of freedoms, food, joy, and basic necessities. In so many ways, mankind often destroys mankind, intentionally and unintentionally.

This is the message embedded in this line. If man took Nature’s lead and instead sought to encourage a sense of unity, perhaps there would be more “fair works” in our members.