the word is used here as a personification of melancholy, or low spirits. It was not an uncommon affectation in England at this time. A letter to the 'Spectator', No. 53, calls it "the distemper of the great and the polite."
Umbriel, who in accordance with his nature now proceeds to stir up trouble. Compare Canto I, ll. 63-64.
The bitter east wind which put every one into a bad humor was supposed to be one of the main causes of the spleen.
the goddess of the spleen. Compare l. 79.
the modern dressing-gown. The line means that whenever a fashionable beauty bought a new dressing-gown she pretended to be ill in order to show her new possession to sympathetic friends who called on her.
these are the visions, dreadful or delightful, of the disordered imagination produced by spleen.
like the serpent which Milton describes in 'Paradise Lost', IX, 501-502, "erect amidst his circling spires."
angels coming to help their votaries. The word "machine" here has an old-fashioned technical sense. It was first used to describe the apparatus by which a god was let down upon the stage of the Greek theater. Since a god was only introduced at a critical moment to help the distressed hero, the phrase, "deus ex machina," came to mean a god who rendered aid. Pope transfers it here to angels.
Pope now describes the mad fancies of people so affected by spleen as to imagine themselves transformed to inanimate objects.
a little jar. Homer ('Iliad', XVIII, 373-377) tells how Vulcan had made twenty wonderful tripods on living wheels that moved from place to place of their own accord.
Pope in a note to this poem says that a lady of his time actually imagined herself to be a goose-pie.
so Æneas bore a magic branch to protect him when he descended to the infernal regions ('Æneid', VI, 136-143).
a sort of fern which was once supposed to be a remedy against the spleen.
a form of spleen to which women were supposed to be peculiarly liable, something like our modern hysteria. It seems to have taken its name from the fogs of England which were thought to cause it.
Belinda, who had always been so light-hearted that she had never been a victim of the spleen.
a liqueur made by distilling brandy with the rind of citrons. It was a fashionable drink for ladies at this time.