Explain how and why David Ricardo and J.S Mill are classical theorists.

Classical and Neo-classical economics

Classical economic theory and neo-classical economic theory are often differentiated along several different axis; for example, classical economic theory, it is sometimes alleged, considers labor, land, rent, and capital in separate, isolated, variables whereas neo-classical economic theory integrates these variables into a single, unified economic theory.
First, explain how and why David Ricardo and J.S Mill are classical theorists.
Second, show how one or the other or both of these theorists is attempting to develop a comprehensive, integrated, internally consistent account for all social and economic landscape.

Please put more effort to answer second part than first one.

Please refer these books
– David Ricardo, Principle of Political Economy and Taxation
– JS Mill, On Liberty

No need to make a general introduction and conclusions

Thank you