Zamenhof gave a lot of beautiful speeches. This one makes me cry every time I read it. It's a lot more eloquent in the original Esperanto, but here is a translation into English that I've made.
The speech was made during a period of intense nationalist violence in Zamenhof's home region. Also at the time of the speech, some members of the Esperanto community thought that Zamenhof's idealism was scaring people away from Esperanto. They wanted to advertise and use Esperanto solely as an instrument for international business and communication and to drop any discussion of world peace. A few years earlier Zamenhof had reluctantly endorsed some of their ideas.
In this speech Zamenhof clarifies that he still sees the pursuit of world peace as the primary goal of Esperanto and he makes a plea for people in the Esperanto community (and beyond) to not lose their idealism. For more about Zamenhof and his political ideas, see here, and here.
