'Sokutenkyosi' represents a very important literary and philosophical idea of Soseki's later life; it is even recognized as a keyword that decodes the greater part of his works. There are many explanations about this term from different angles, for Soseki himself didn't write anything directly about it. This paper argues that 'sokutenkyosi' means spontaneity and egolessness in terms of life philosophy and, in terms of literary theory, naturalness and transcendence without the author's interference in his own works. After verifying the life philosophy of Confucianism, Taoism and Zen Buddhism against the term, this author concludes that 'sokutenkyosi' is more closely related to both Taoism and Zen Buddhism and that, as his short stories and many of his letters reveal, the term is a literary idea which can be practiced, however, as far as Soseki is concerned, it is just a motto for himself.