How did John Locke distinguish simple ideas from complex ideas?

In his An Essay Concerning Human Understanding, John Locke distinguishes between simple and complex ideas based on their origin and their susceptibility to analysis.12

• Simple Ideas: These are the basic materials of knowledge derived directly from sense experience or reflection. Because they are fundamental, they cannot be analyzed or broken down into smaller components.12
• Complex Ideas: These are formed by the mind through the process of compounding, which involves combining various simple and complex ideas. Unlike simple ideas, complex ideas can be analyzed and deconstructed into the constituent parts from which they were composed.12

For example, the complex idea of a snowball can be analyzed into the simple ideas of whiteness, roundness, and solidity. While the complex idea can be broken down, those individual simple ideas cannot be further reduced. Locke viewed the identification and analysis of these ideas as a primary function of philosophical inquiry.12