Dr. Durga Das Basu was an illustrious son of Bengal and a legal scholar of universal eminence. Not only did he rise to be an Hon’ble judge of the High Court of Calcutta, but he also earned international recognition and fame for his monumental writings, especially, but not exclusively, on the Constitution of India which he started producing soon after the commencement of our Constitution in 1950. For his monumental works he was awarded numerous academic degrees and honours. In view of Dr. Basu’s vast universe of law and life, I had difficulty in deciding the theme of my lecture which could be anything different from what he had covered in all details within the legal domain dearest to him viz. constitutional law. In the process of deciding the theme of my lecture, I realised that even though the concept of constitutionalism as an aspect of the Constitution of India, as is noted below, could not escape Dr. Basu’s attention, it had not been discussed in all its details that have partly developed since his departure from the scene.