How did John Locke explain the mind’s formation of complex ideas from simple sensory materials?

John Locke, a central figure in empiricism, rejected the doctrine of innate ideas, arguing instead that the mind begins as a tabula rasa, or blank slate. According to Locke, all knowledge is derived from two primary sources: sense experience and reflection.123

These sources provide the mind with "simple ideas," which are the basic building blocks of knowledge—such as the sensation of a specific color, sound, or taste. Because these simple ideas are received directly through experience, they cannot be further analyzed or broken down.13

The mind forms "complex ideas" through the process of compounding, where it actively combines these simple ideas (and other complex ones) into more elaborate concepts. For instance, the complex idea of a snowball is formed by the mind combining the simple ideas of whiteness, roundness, and solidity. Consequently, Locke viewed philosophical inquiry as a process of analyzing complex ideas to identify the simple sensory materials from which they are composed.13