Let [i]p[/i] and [i]q[/i] (through [i]C[/i]) be the polars of two self-conjugate points [i]P[/i] and [i]Q[/i] on a line [i]c[/i]. Let [i]R[/i] be a point on [i]p[/i], distinct from [i]C[/i] and [i]P[/i]. Let its polar [i]r[/i] meet [i]q[/i] in [i]S[/i]. Then [math]S = q\cdot r[/math] is the pole of [math]QR = s[/math], which meets [i]r[/i] in [i]T[/i]. Also [math]T = r \cdot s[/math] is the pole of [math]RS = t[/math], which meets [i]c[/i] in B. Finally, [math]B = c \cdot t[/math] is the pole of [math]CT = b[/math], which meets [i]c[/i] in [i]A[/i], the harmonic conjugate of [i]B[/i] with respect to [i]P[/i] and [i]Q[/i].