Edgar first assumes the disguise of Poor Tom as Lear and the Earl of Gloucester enter the cave in which Edgar is hiding. Since Edgar was banished, similar to Kent, who is also present later in this act, he must conjure up a disguise. Why does Edgar chose the repulsive beggar that Poor Tom is? Well, remember that Poor Tom represents the popular belief of the insane during the Elizabethan era. Therefore, he is the perfect disguise. No one would ever suspect Poor Tom of being Edgar, because Edgar is a very pleasant man, while Tom is completely repulsive. Furthermore, the reason Edgar chose this disguise is contained within his soliloquy as he is becoming Poor Tom:
Whiles I may 'scape,
I will preserve myself; and am bethought
To take the basest and most poorest shape
That ever penury, in contempt of man,
Brought near to beast; my face I'll grime with filth,
And with presented nakedness outface
The winds and persecutions of the sky.
The country gives me proof and precedent
Of Bedlam Beggars, who, with roaring voices,
Strike in their numb'd and mortified bare arms
Pins, wooden pricks, nails, sprigs of rosemary;
And with this horrible object, from low farms,
Poor pelting villages, sheep-cotes, ad mills,
Sometime with lunatic bans, sometime with prayers,
Engorece their charity. Poor Turlygod! poor Tom!
That's something yet: Edgar I nothing am.
According to William C. Carroll (1987), "Edgar's self-description follows the tradition closely, as he takes on the part with all it's theatrical implications-grimed face, presented nakedness, roaring voice- and disappears into 'nothing,' into Tom's body." Edgar chose this disguise with the intention of being someone so commonly known by the people that they would never suspect that the disguise wasn't in fact natural.
This soliloquy is also a method for Shakespeare to further connect with the audience. He is entertaining what he presumes will be the prevailing notion concerning the appearance and personality of the typical beggar, which is what Edgar has essentially been reduced to. Poor Tom is an incredibly repulsive character, who will receive no sympathy from the audience. However, the fact that Edgar has been reduced to this state will make the audience think, and potentially realize that anyone could be reduced this lowly state. After all, Edgar was one of the most noble and favored people in the kingdom. So, by making Edgar take on this disguise, Shakespeare could potentially cause the audience gain some sympathy for real life beggars. In addition, it could also potentially refute some of their beliefs concerning madness, and realize that they too could become mad, which in return should cause them to gain some sympathy for actual people who are mad.
The reason that Shakespeare chooses Poor Tom to be Edgar's disguise is to prove a major point concerning the origin of madness. Lear, the hero of the play, demonstrates to the audience Shakespeare's beliefs concerning the true origin of madness....