The old thane of Cawdor has confessed to high treason, and has recently been executed, and King Duncan replies as follows,
"There’s no art
To find the mind’s construction in the face.
He was a gentleman on whom I built
An absolute trust."
The idea of deception can be found in Browning's poem, in many places.
"And all her yellow hair displaced, And, stooping, made my cheek lie there,
And spread, o'er all, her yellow hair,"
The implicit message is fairly straight forward, as it informs us that this woman named 'Porphyria' has yellow hair, presumably meaning blonde. Yet Browning chose the word yellow purposely. This is because yellow has many connotations that we usually link with the colour, such as, warning, caution, sickness and disease. Although at first the reader may assume Browning only meant blonde hair, which links to the idea of deception. This idea of caution, sickness and deception could be seen in Macbeth when the prophecies have been revealed to Macbeth and Banquo and the first prophecy happens. Macbeth starts to fantasize about being the king as if it is an illness, and his friend Banquo warns him to be cautious of the witches prophecies as they may not be as beneficial as they seem.
Leading on from the previous point of illnesses, during the time period that this poem was written, Porphyria was a mental illness that could cause hallucinations, which could mean that Browning intended for this "woman" to be nothing but a hallucination... the man being deceived by his mind. This may why when entering it was written that she glided in. "When glided in Porphyria".
The hallucinations may have been similar to the hallucinations that Macbeth experienced due to the guilt, "Is this a dagger I see before me?"
It could also be interpreted as someone being described as very beautiful and enticing, but is in actuality quite deadly, in the same way as the throne seemed very appealing to Macbeth, but it ultimately lead to his demise.
H Ahmad C