Shakspeare understood this well, as he understood everything that belonged to his art.

Who does not sympathise with the rapture of Ariel, flying after sunset on the wings of the bat, or sucking in the cups of flowers with the bee?
Who does not shudder at the caldron of Macbeth?
Where is the philosopher who is not moved when he thinks of the strange connection between the infernal spirits and "the sow's blood that hath eaten her nine farrow ?" But this difficult task of representing supernatural beings to our minds, in a manner which shall be neither unintelligible to our intellects nor wholly inconsistent with our ideas of their nature, has never been so well performed as by Dante.

I will refer to three instances, which are, perhaps, the most striking:--the description of the transformations of the serpents and the robbers, in the twenty-fifth canto of the Inferno,--the passage concerning Nimrod, in the thirty-first canto of the same part,--and the magnificent procession in the twenty-ninth canto of the Purgatorio.
The metaphors and comparisons of Dante harmonise admirably with that air of strong reality of which I have spoken.

They have a very peculiar character.

He is perhaps the only poet whose writings would become much less intelligible if all illustrations of this sort were expunged.