Answer by Raghu Venkataraman:
The ability to stay curious and be open to change.
That's really two, but the second is a vital corollary to the first.
The first calls for an endless desire to know more about the world in order to make a difference (positive, one hopes!), to the people around you, your community, city, nation or the world.
The second – the need to be open to change, is to be able to absorb the outcomes of your learnings from your curiosity in order to improve on your own foibles and weaknesses, and thereby also to improve your capability to affect changes on the people and environment around you.
When you lose curiosity, you are effectively dead.
As Bernard Shaw put it:
"All progress depends on the unreasonable man."
One man, among many illustrious counterparts, who spent his entire life with endless curiosity, plumbing the secrets of life in the scientific pursuit is Isaac Newton:
“I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.”
― Isaac Newton