Brian has a detailed post about Ashura observances in Bahrain. In the course of the post he mentioned a quote about Imam Husain AS by Mahatma Gandhi; I was motivated by this to go looking for other quotations on Imam Husain and the sacrifice at Karbala by other notable persons. I have reprinted a few of the more interesting ones below.
"The best lesson which we get from the tragedy of Karbala is that Husain and his companions were rigid believers in God. They illustrated that the numerical superiority does not count when it comes to the truth and the falsehood. The victory of Husain, despite his minority, marvels me!" -- Thomas Carlyle
"In a distant age and climate, the tragic scene of the death of Hosein will awaken the sympathy of the coldest reader." -- Edward Gibbon
"I learnt from Hussein how to achieve victory while being oppressed." -- Mahatma Gandhi
"If Husain had fought to quench his worldly desires…then I do not understand why his sister, wife, and children accompanied him. It stands to reason therefore, that he sacrificed purely for Islam." -- Charles Dickens