Along with Schopenhauer, Samuel Beckett was thought to be particularly influenced by Descartes (who y'all know well enough) and, also, Arnold Geulincx. Who? Well, a bit more information below which comes from the sadly rather bare Arnold Geulincx resource site which was put together by Professor Anthony Uhlmann (Beckett and the Philosophical Image and Beckett and Poststructuralism).
Arnold Geulincx and his Works by Professor J.P.N. LAND (1891; originally in MIND: a quarterly review of psychology and philosophy XVI):
Since Brucker’s time the name of Arnold Geulincx has been well known to every student of philosophy in connexion with the doctrine of Occasionalism... Within the last years, many monographs have appeared dealing with various points of his doctrine, and with his relations to Descartes, Spinoza and Leibniz. His writings, meanwhile, have long been so rare that hardly anyone can have seen them all together, and, till a short time ago, no more was known of the circumstances of his life than was contained in the meagre notice of Paquot (1768)... Something remained to be discovered as to Geulincx’ last years, during which he taught at Leyden and wrote his systematic works. This I have myself extracted from the archives of our town and university (more...)