What was nature's holy plan?

In the poem "Lines Written in Early Spring" by William Wordsworth, "nature's holy plan" appears to be enjoying life. As the speaker sits in a grove and ponders the plant and animal life existing there, they note that joy is present throughout all sentient beings. The speaker sees joy in the flowers of spring, in the birds as they hop about and play, and in the budding trees as they stretch limbs out into the fresh spring air. The speaker wonders if this utter joy of living is, indeed, nature's plan. The speaker then thinks about the horrors that humans have committed against one another and feels a strong juxtaposition of sadness for the state of humans compared to the simple joy that non-human life seems to feel at merely being alive.