There is a lot of reference to blood in Macbeth. Does the blood have a metaphorical meaning?Do you have any quotes that support this?

Though the word does not even occur, the idea or image is
present even to inundation, a flood of blood, such as spurts from a stuck pig. The same
thing is true of Lady Macbeth's ghastly, "Yet who would have thought the old man to have
had so much blood in him?" (V.i.45), and accounts - along with the coarse insolence of
her reference to the King, guest, benefactor, as "old man" - for the power of this
celebrated line. We have blood not only everywhere, then, but swarming. Moreover, in a
number of other very powerful passages, the audience or reader is compelled to imagine
blood for itself even more specifically than in the "swine" passage. "It will have
blood, they say; blood will have blood," Macbeth mutters to himself (III.iv.122). Here
the mysterious "It" is explained immediately - murder cries out for retribution - and
yet the force of its initial, dreadful vagueness is not dissipated by the explanation.
The horrible suggestion is in fact made by the explanation that anything in the universe
not at once identified as something else is blood; and iteration of the actual word
thrice in one line assists the suggestion. As a man thinks of his wife not by name but
as "she" and "her", so Macbeth thinks of his topic - blood, the murder - as "it":
central, permanent, a point to which other things are referred. The implied picture of
his mind makes one shudder.