 Although occasionally there may be references to a variety of texts, for reasons of space, the focus here will be on Carmen de cometa [Poem of the Comet] and the Letter to Christopher Clavius, for they best serve as a bridge to Quod nihil scitur/That Nothing is Known (QNS/TNK), the work that made Sanches famous and continues to be studied; either because of its own intrinsic merits or in connection with  René Descartes’ (1596–1650)  “radical doubt”, and other sixteenth and seventeenth century sceptics like Pierre Charron (1541–1603) or  Montaigne.  The essay will consequently begin with Carmen de cometa (1578)/Poem of the Comet, move to Sanches’ “Letter to Christopher Clavius”, and will lastly deal with Quod nihil scitur (1581)/That Nothing is Known (1988, TNK).