Possible Clues:

• Two-dimension math
• Study that lacks depth?
• Math class
• Subject with no depth?
• Subject of a Euclidean treatise
• By a quiet lane, little George and me take a shot at Euclid's study
• First subject in Euclid's "Elements"
• Just figure how one might use this for shaving
• High school math course
• 2-D study