What do you think Wordsworth meant by "the burden of the mystery" in line 39 of "Lines Composed a Few Miles Above Tintern Abbey"?

Long after he saw the wonders of nature along the river Wye, Wordsworth credits his memory of "these forms of beauty" (line 24) with "tranquil restoration" (line 31). In other words, just thinking about these sights can restore his peace of mind. He also credits these memories with "another gift," (line 37), which is the mood

In which the burthen of the mystery,

In which the heavy and the weary weight

Of all this unintelligible world

Is lighten'd (lines 39-42).

In other words, when Wordsworth recalls the peacefulness of these scenes from nature, which he saw five years before, the mystery of our existence and the burden this mystery places on us become lighter. He no longer struggles with the questions that plague him about life and its meaning; instead, he is able to be at peace. "The burthen of the mystery" is Wordsworth's poetic way of referring to everything people question about life. They are burdens because our purpose and meaning pose unanswerable questions.