Invulnerability is associated with air and insubstantiality in the three occurrences of the word 'invulnerable.' There are "th' [invulnerable] clouds of heaven" (KiJ 2.1.252). Marcellus say that the Ghost is "as the air, invulnerable" (Ham.1.1.145). Ariel mocks the "men of sin":
My fellow ministers
66 Are like invulnerable. If you could hurt,
67 Your swords are now too massy for your strengths,
68 And will not be uplifted. (Tem.3.3.66)
In this passage, the emphasis on the material weight of mortal weapons underscores the invulnerability of insubstantial agents.
17 September 1999