Footfalls above "we would see the tracing on the stage floor of a tremendously elongated variation of the figures 8 turned on its side … the mathematical symbol for infinity." Beckett was also indebted to the French psychologist Pierre Janet for his conception of hysterical behaviour. In his overview of Janet's work, Robert Woodworth in his "Contemporary Schools of Psychology", a work Beckett read, pays particular attention to Janet's description of the "hysterical paralysis of one arm", which Beckett incorporated, into May's posture. There are a number of analogies between "Footfalls" and Janet's work with a patient called Irène: He lists
Plane at infinity does make it look "special" in comparison to the other planes of the space. If the affine 3-space is real, formula_2, then the addition of a real projective plane formula_3 at infinity produces the real projective 3-space formula_4. Since any two projective planes in a projective 3-space are equivalent, we can choose a homogeneous coordinate system so that any point on the plane at infinity is represented as ("X":"Y":"Z":0). Any point in the affine 3-space will then be represented as ("X":"Y":"Z":1). The points on the plane at infinity seem to have three degrees of freedom, but homogeneous coordinates are equivalent