If they but hear perchance a trumpet sound,
Or any air of music touch their ears,
You shall perceive them make a mutual stand,
Their savage eyes turn'd to a modest gaze.
By the sweet power of music: therefore, the poet
Did feign that Orpheus drew trees, stones, and floods:
Since nought so stockish, hard, and full of rage,
But music for the time doth change his nature.
The man that hath no music in himself,
Nor is not mov'd with concord of sweet sounds,
Is fit for treasons, stratagems, and spoils;
The motions of his spirit are dull as night,
And his affections dark as Erebus.
Let no such man be trusted.—Mark the music.

L. 97. Portia and Nerissa.

Por. ... Music! hark!

Ner. It is your music, madam, of the house.

Por. Nothing is good, I see, without respect.
Methinks, it sounds much sweeter than by day.

Ner. Silence bestows that virtue on it, madam.

Por. The crow doth sing as sweetly as the lark,
When neither is attended; and I think,
The nightingale, if she should sing by day,
When every goose is cackling, would be thought
No better a musician than the wren.
How many things by season season'd are
To their right praise, and true perfection.

Here is an example of a superstitious meaning attaching to supposed mysterious music.

There are very few cases of this kind in Shakespeare—i.e., where the music of the stage is an integral part of the drama.

Antony and Cleop. IV, iii, 12. Music of hautboys under the stage.