The Buddha's epistemology has been compared to empiricism, in the sense that it was based on experience of the world through the senses. The Buddha taught that empirical observation through the six sense fields (ayatanas) was the proper way of verifying any knowledge claims. Some suttas go further, stating that "the All", or everything that exists ("sabbam"), are these six sense spheres (SN 35.23, Sabba Sutta) and that anyone who attempts to describe another "All" will be unable to do so because "it lies beyond range". This sutta seems to indicate that for the Buddha, things in themselves or noumena, are beyond our epistemological reach ("avisaya").