Secret ministry

I think "the secret ministry of frost" has to do with a return to nature. The speaker is surrounded by nature in the poem and although he is in "solitude" the stanza does not express loneliness, while the stanza of his memory and the man-made school does.  He imagines a future of natural life for his child where "all seasons shall be sweet to thee".  Even winter, which is typically thought of as a harsh side of nature, is represented gently by Coleridge.  Nature is also aligned with religion around line 60 with the "eternal language" and "Great universal Teacher".