Secretary General Ban Ki-moon paid tribute to former Indian president A.P.J. Abdul Kalam's "inspiration" to the world on Friday during a visit to the Indian Mission in New York as a special gesture of condolence.Ban said: "The outpouring of grief around the world is a testament of the respect and inspiration he has garnered during and after his presidency.""The UN joins the people of India in sending our deepest condolences for this great statesman," he added.He signed a book of condolence at the mission during the visit. Over the past two days ambassadors of UN member states have been visiting the mission to sign the book and offer their condolences on the death of the Indian statesman.