Madness+vs+Sanity

The character who introduces the motif of Madness & Sanity, or introduces it as an element in the play is Hamlet. It's an important theme in the play...

Lines about madness:

Lines 693-725, where Horatio and Marcellus is trying to prevent Hamlet, dissuading him from going with the ghost, warning that he could go mad. With folly, at least from the perspective of audience, he staunchly refuses.

Exeunt Ghost and Hamlet.
 * **[|Marcellus].** Look with what courteous action It waves you to a more removed ground. But do not go with it!
 * **[|Horatio].** No, by no means!
 * **[|Hamlet].** It will not speak. Then will I follow it.
 * **[|Horatio].** Do not, my lord!
 * **[|Hamlet].** Why, what should be the fear? I do not set my life at a pin's fee; And for my soul, what can it do to that, Being a thing immortal as itself? 700 It waves me forth again. I'll follow it.
 * **[|Horatio].** What if it tempt you toward the flood, my lord, Or to the dreadful summit of the cliff That beetles o'er his base into the sea, And there assume some other, horrible form Which might deprive your sovereignty of reason And draw you into madness? Think of it. The very place puts toys of desperation, Without more motive, into every brain That looks so many fadoms to the sea 710 And hears it roar beneath.
 * **[|Hamlet].** It waves me still. Go on. I'll follow thee.
 * **[|Marcellus].** You shall not go, my lord.
 * **[|Hamlet].** Hold off your hands!
 * **[|Horatio].** Be rul'd. You shall not go.
 * **[|Hamlet].** My fate cries out And makes each petty artire in this body As hardy as the Nemean lion's nerve. //[Ghost beckons.]// 720 Still am I call'd. Unhand me, gentlemen. By heaven, I'll make a ghost of him that lets me!- I say, away!- Go on. I'll follow thee.
 * **[|Horatio].** He waxes desperate with imagination.

"I will be brief. Your noble son is mad. Mad call I it; for, to define true madness, What is't but to be nothing else but mad?" Polonius talking about Hamlet to the King & Queen .