Sentence:  ... at last, — this is the point to be marked, - they can see things in this <WSD>Parnassian</WSD> way and describe them in this <WSD>Parnassian</WSD> tongue, without further effort of inspiration. 
Meaning of the word marked with <WSD> tags:  From Gerard Manley Hopkins' writings: describing a style of poetry or language which can only be created by poets, but not in the language of inspiration.