Myself an enemy to all other joys
     Which the most precious square of sense professes, . . .

Regan will strip off all the human senses so long as she 
possesses Lear’s love. 
     The allusion to “the most precious square of sense” 
shows Shakespeare doing an almost scholastic demonstration 
of the need for a ratio and interplay among the senses as the 
very constitution of rationality. His theme in Lear is that of 
John Donne in An Anatomy of the World :

     ’Tis all in pieces, all coherence gone;
     All just supply, and all Relation:
     Prince, subject, Father, Son, are things forgot, 
     For every man alone things he hath got
     To be a Phoenix . . .