Well, a great thinker and poet is ever thus--floating between the universe of spirit and the universe of matter.
By his mind he belongs to the region of pure mind,--the ethereal state; but the hard necessity of living keeps him down in the world of sense and grossness and struggle.

On the other hand the butterfly, freely moving in a finer element, better represents the state of spirit or soul.
What is the use of being dissatisfied with nature?
The best we can do is to enjoy in the imagination those things which it is not possible for us to enjoy in fact.
Emancipate through passion And thought, with sea for sky, We substitute, in a fashion, For heaven--poetry: Which sea, to all intent, Gives flesh such noon-disport, As a finer element Affords the spirit-sort.
Now you see where the poet's vision of a beautiful butterfly has been leading his imagination.

The nearest approach which we can make to the act of flying, in the body, is the act of swimming.

The nearest approach that we can make to the heavenly condition, mentally, is in poetry.

Poetry, imagination, the pleasure of emotional expression--these represent our nearest approach to paradise.