Dependent-origination, possibly the most fundamental Buddhist philosophical principle, is generally understood as a description of all that exists. Mental as well as physical phenomena are believed to come into being only in relation to, and conditioned by, other phenomena. This paper argues that such an understanding of pratītya-samutpāda is mistaken with regard to the earlier meanings of the concept. Rather than relating to all that exists, dependent-origination related originally only to processes of mental conditioning. It was an analysis of the (...) self, not of reality, embedded in the Upaniṣadic search for the ātman. The teaching also possessed important ontological implications regarding the nature of the relation between consciousness and reality. These implications suggest that rather than things being conditioned by other things, they are actually conditioned by consciousness. (shrink)