Illusion

What hands are here? ha! they pluck out mine eyes.
Will all great Neptune's ocean wash this blood
Clean from my hand?

The loss of a hand or leg may also create an illusion like itching feeling in the sole of the foot that is not there.

Illusion is better explained as psychic creation of an oppressed brain trying to cope up with troubled situations.
A result of crime; as seen in Macbeth; the illusion of the knife may be the action of a fevered mind.

art thou but

A dagger of the mind, a false creation,

Proceeding from the heat-oppressed brain?

I see thee yet, in form as palpable

As this which now I draw.

The most common illusion is the optical illusion, seeing things that are not actually there. From a mirage to the seeing of 3D figures where there are none—all belong to this category.

The ventriloquist creates an illusion of sound.

Do you know that a successful mime artist also creates an illusion?

unnatural deeds
Do breed unnatural troubles: infected minds
To their deaf pillows will discharge their secrets:

Quotes: Macbeth-Shakespeare

Picture: Thanks to Wikipedia