Secant line a circle in the Euclidean plane, a line joining two of them would be a 2-secant (or "bisecant") and a line passing through only one of them would be a 1-secant (or "unisecant"). A unisecant in this example need not be a tangent line to the circle. This terminology is often used in incidence geometry and discrete geometry. For instance, the Sylvester–Gallai theorem of incidence geometry states that if points of Euclidean geometry are not collinear then there must exist a 2-secant of them. And the original orchard-planting problem of discrete geometry asks for a bound on the number of
When a white horse is not a horse be found in the widely known "Happiness of Fish" dialogue in "Zhuangzi" (17, tr. Watson 1968:188-9). Huizi says "You're not a fish [子非魚] — how do you know what fish enjoy?" (denying that Zhuangzi is a member of the class of fish) and Zhuangzi replies "You're not I [子非我], so how do you know I don't know what fish enjoy?" (denying that the individuals Huizi and Zhuangzi are identical). Beyond the inherent semantic ambiguities of "Baima fei ma", the first line obscurely asks "ke hu" "Can it be that …?". This dialogue could be an attempted proof that a white