Gilbert Ryle was a British philosopher, principally known for his critique of Cartesian dualism, for which he coined the phrase "ghost in the machine". Some of Ryle's ideas in philosophy of mind have been called logical behaviourist. In his best-known book, The Concept of Mind (1949), he writes that the "general trend of this book will undoubtedly, and harmlessly, be stigmatised as 'behaviourist'." Having studied the philosophers Bernard Bolzano, Franz Brentano, Alexius Meinong, Edmund Husserl, and Martin Heidegger, Ryle suggested that the book instead "could be described as a sustained essay in phenomenology, if you are at home with that label."