Light thickens and the crow
    Makes wing to the rooky wood.
       . . . . . 
    Now spurs the lated traveller apace
    To gain the timely inn.

Macbeth (generally speaking) is done upon a stronger and more systematic principle of contrast than any other of Shakespeare’s plays.  It moves upon the verge of an abyss, and is a constant struggle between life and death.  The action is desperate and the reaction is dreadful.  It is a huddling together of fierce extremes, a war of opposite natures which of them shall destroy the other.  There is nothing but what has a violent end or violent beginnings.  The lights and shades are laid on with a determined hand; the transitions from triumph to despair, from the height of terror to the repose of death, are sudden and startling; every passion brings in its fellow-contrary, and the thoughts pitch and jostle against each other as in the dark.  The whole play is an unruly chaos of strange and forbidden things, where the ground rocks under our feet.  Shakespeare’s genius here took its full swing, and trod upon the furthest bounds of nature and passion.  This circumstance will account tor the abruptness and violent antitheses of the style, the throes and labour which run through the expression, and from defects will turn them into beauties.  ’So fair and foul a day I have not seen,’ &c.  ‘Such welcome and unwelcome news together.’  ’Men’s lives are like the flowers in their caps, dying or ere they sicken.’  ’Look like the innocent flower, but be the serpent under it.’  The scene before the castle-gate follows the appearance of the Witches on the heath, and is followed by a midnight murder.  Duncan is cut off betimes by treason leagued with witchcraft, and Macduff is ripped untimely from his mother’s womb to avenge his death.  Macbeth, after the death of Banquo, wishes for his presence in extravagant terms, ‘To him and all we thirst,’ and when his ghost appears, cries out, ‘Avaunt and quit my sight,’ and being gone, he is ‘himself again’.  Macbeth resolves to get rid of Macduff, that ’he may sleep in spite of thunder’; and cheers his wife on the doubtful intelligence of Banquo’s taking-off with the encouragement—­’Then be thou jocund:  ere the bat has flown his cloistered flight; ere to black Hecate’s summons the shard-born beetle has rung night’s yawning peal, there shall be done—­a deed of dreadful note.’  In Lady Macbeth’s speech, ‘Had he not resembled my father as he slept, I had done’t,’ there is murder and filial piety together, and in urging him to fulfil his vengeance against the defenceless king, her thoughts spare the blood neither of infants nor old age.  The description of the Witches is full of the same contradictory principle; they ’rejoice when good kings bleed’; they are neither of the earth nor the air, but both; ‘they should be women, but their beards forbid it’; they take all the pains possible to lead Macbeth on to the height of his ambition, only to betray him in deeper consequence, and after showing him all the pomp of their art, discover their malignant delight in his disappointed hopes, by that bitter taunt, ’Why stands Macbeth thus amazedly?’ We might multiply such instances everywhere.