As a water researcher/author/poet - this poem speaks to me on many levels.
The last two lines, Bear only purfumes and the scent, o healing herbs to just men's fields!
This is the completion of a thought whereby the fecund marshes and wetlands create conditions that produce prodigious blooms of flowers and herbs along their banks. Thus, the drifting meadow of the air carries the purfume to the cultivated fields of local farmers. Air that is saturated with moisture will absorb and carry the scent of flowers and herbs in a stronger fashion than thin, dry air that evaporates upward and cannot absorb or hold the scent of plants. Daisies, which are flowers that open during the day and close at night, are a favorite flower of poets because it not only heralds the beginning of a new season - but because daisies also have herbal healing powers that made it popular amongst country folk. The same goes with odoriferous violets - which is another scented spring flower.
Highly serene, descriptive and metaphorical except for the last three lines...
'Spirit of the lake and seas and rivers,
Bear only purfumes and the scent
Of healing herbs to just men's fields! '....Does it mean that where there is mist perfumes and scent are not diffused properly...but they do just to the far away field men....or is it perfume and scent of the healing herbs are just for humans only....puzzling is that just men (or justman)
A poem with the theme of mist and water vapour beneath the immersion layer. Water in various forms but no rain. It reminds of the earth before the flood, when according to the Bible it had never rained, but the air was full of water vapour. The poet is calling upon the ‘Spirit of the lake and seas and rivers’ to
‘Bear only purfumes and the scent
Of healing herbs to just men's fields! ’
Like incense burned in offering to God or at religious ceremonies, these just men, apparently deserve a special blessing. It appears to be an idyllic paradise setting the poet is imaging or describing, a perfumed Eden.
Nature has created misty dream like atmosphere with clouds, dews over meadows spreading over rivers, seas, etc. with herbal scent and perfume influencing man's fields! A scene quite refreshing to lonely persons of seclusion and out of mood indeed this could be a healing balm so to say! A nice situation Thoreau has created in his poem!