There must be some other possibility than death or lifelong penance … some meeting, some intersection of lines; and some cowardly, hopeful geometer in my brain tells me it is the angle at which two lines prop each other up, the leaning-together from the vertical which produces the false arch. For lack of a keystone, the false arch may be as much as one can expect in this life. Only the very lucky discover the keystone.
Wallace Stegner, Angle of Repose
