New Delhi, Jan. 26 -- Today is no ordinary Republic Day. 2020 marks the 70th anniversary of our Constitution. In 1950, many questioned how long it would last. So to have completed the biblical span of three-score-years-and-ten is no mean achievement. There are only a few constitutions - and certainly in the third world there is no other - that have lasted so long. Why that's happened is an important question, but I want to start by delving into the depths of our Constitution. The challenge of survival can be raised after that....