Being and Time raises the problem of "authenticity," that is, the potentiality or otherwise for mortal "Dasein" to exist "fully" enough that it might actually understand being. Heidegger is clear throughout the book that nothing makes certain that "Dasein" is capable of this understanding. Finally, this question of the authenticity of individual "Dasein" cannot be separated from the "historicality" of "Dasein". On the one hand, "Dasein", as mortal, is "stretched along" between birth and death, and thrown into its world, that is, thrown into its "possibilities", possibilities which "Dasein" is charged with the task of assuming. On the other hand, "Dasein's" access to
Thomas Vaughan (philosopher) out with an alchemical collaborator, Edward Bolnest, over money matters and alleged broken promises, and the matter came to litigation after Bolnest had threatened violence. Vaughan was accused as part of this affair of spending "most of his time in the study of Naturall Philosophy and Chimicall Phisick". He is reported as having confessed that he had "long sought and long missed... the philosopher's stone." Thomas Vaughan (philosopher) Thomas Vaughan (1621 − 27 February 1666) was a Welsh philosopher and alchemist, who wrote in English. He is now remembered for his work in the field of natural magic. A Royalist