Reid admits that, when the consciousness that has become aware of itself surveys that which lies within its own horizon, it finds nothing else there but transient pictures. These pictures in themselves bring to the mind no experience of a lasting existence outside itself. There is no firm evidence of the existence of either an outer material world to which these pictures can be related, or of an inner spiritual entity which is responsible for them. To be able to speak of an existence in either realm is impossible for a philosophy which confines its attention solely to the mere picture-content of the waking consciousness.