 Several illustrations of indiscriminate sampling are common in the literature, but some are more helpful than others. One is a hypothetical scenario in which two genetically and phenotypically identical twins are walking together; one is struck by lightning whereas the other lives to reproduce. (The example seems to have its origins in Scriven 1959 and Mills and Beatty 1979, although these authors were making a point about fitness, not about drift). This is an unfortunate illustration in part because it is too easy to get caught up in the question of whether the twins are really genetically and physically identical, but, more importantly, it is misleading because in fact, drift requires heritable variation, just as selection does. The lightning example is also problematic because it makes drift seem exceptional and catastrophic, whereas it is generally considered to be pervasive (i.e., occurring in all populations) and not necessarily due to catastrophic or unusual events. Others (e.g., Matthen and Ariew 2002; Walsh, Lewens, and Ariew 2002) use a series of coin tosses as an illustration of drift, but this could be challenged because it encourages binary thinking, instead of allowing for multiple variants with multiple outcomes, and because it is unclear what the “population” of coin flips amounts to.