The answer is the horizon line.
Macbeth is a tragedy written by William Shakespeare, believed to be first presented in 1606. After ordering his men to murder his good friend Banquo, Macbeth sees the ghost of his friend, during a dinner with some nobles. Being confronted by his murdered victim, Macbeth loses self-control and completely ignoring his important guests, he interacts and discusses with the ghost. His distress and despair are signs that he lost control and he surrenders to his extreme guilt. Shakespeare wants to show that our evil acts will eventually come back to haunt us.
The answer is basso continuo
From the Italian language sometimes abbreviated as b.c is a technique of self-composition and execution and essential from the Baroque period
The basso continuo is played for one or various instruments, typically and harmonic as the keyboard instruments or others as the harp or lute
with the voice of bass simultaneously in charge of an instrument of grave tessitura like the violoncello, bassoon, the viola da gamba, contrabass and sometimes contrabasso.
It also receives the name of simultaneous accompaniment
