The book Cases and Materials on Constitutional Law of India Fons Juris of Foundational Fundamentals presents an in-depth study about the foundational fundamentals of textual Constitution of India. Foundational fundamentals are fons juris of our Constitution. Our Constitution was devised on the basis of "The Constitution of India — Yesterday, Today and Tomorrow", which promotes the understanding of constitutional framework. With diffidence, it brings about familiarity with the key terms, expressions, clauses, cases and chronologies in constitutional law and to articulate informed opinion over important and controversial constitutional issues, particularly relating to Basic Structure, Expounding Philosophy of the textual Constitution, Concepts of the Constitution, Constitutional Law and Constitutionalism, Preamble, Citizenship, Fundamental Rights, Directive Principles of State Policy and Fundamental Duties. With reticent, an attempt has been made to present, for the first time in the study of constitutional law, insights into jural postulates in context and content of correlatives and opposites in relation to fundamental rights, directive principles of State policy and Fundamental Duties. Constitution of India is the soul of our country INDIA that is BHARAT — the Union of States, a pictogram of mutually reciprocal and friendly to each other states; an emblem of indestructible union of destructible units. It is suprema lexof India. It is a symbol of unity in diversity. It is a treasure of national heritage. It is the conscience of our country. It is the sacred gospel of our nation containing the aspirations of WE THE PEOPLE OF INDIA aimed at strengthening the unity, integrity and harmony of the Nation. It is not a seasonal document; it is a permanent document that binds the posterity for ages. In this context, the constitutional textual words, terms, and expressions do not change, but its interpretation undergoes a change having one meaning in one context and somewhat different meaning in another context.