"But unfortunately Locke treated ideas of reflection as if they were another class of objects of contemplation beside ideas of sensation"

In this quote, Samuel Alexander is describing the theorist John Locke's views on concepts of reflection. Locke believed that concepts of reflection were a separate class of things of reflection from concepts of experience. He argued that ideas of reflection were not originated from sensory experience, however rather were the product of the mind's own operations. Locke thought that concepts of reflection were more complicated than ideas of sensation, and that they could be utilized to get understanding about the world. He argued that ideas of reflection could be used to form abstract ideas and to reason about the world. Locke's views on ideas of reflection were influential in the development of contemporary approach.