Sitting in a classroom in the capital, Klaus Seilwinder eagerly discusses philosophical texts, 10 years of living on the streets etched into his face.
"I have a need for education," he says, joining in with today's debate - Political Philosophy: Law and Justice - at the Homeless University.
The university is a new education project, which started in the German capital with the aim of giving homeless people more of social life, although those with a permanent residence can also sign up.
Seminars on subjects including cookery, bible study and philosophy, are taught by volunteers, some of whom were formerly homeless, and take place in locations across Berlin.
"The university has been well-received," said Maik Eimertenbrink, the communications specialist, who initiated the project, following the model of Megaphon-Uni in Graz, Austria, which offers free lectures and workshops, regardless of people's origin or social background.
Eimertenbrink said that normally passers-by would just give people living on the streets a euro and then walk away, but that many wanted to be challenged and to learn.
"They're not stupid, they have something to offer," said the 37-year-old.
For Seilwinder, the classes have helped him to get his life under control – an alcoholic, he has not had a drink for a year-and-a-half, and meanwhile, he has found a secure home and is receiving Hartz IV unemployment benefits.
"The meetings firstly provide structure," said Seilwinder, who was formerly a professional soldier, and goes not only to the philosophy course, but also to theatre and cookery classes, as well as teaching a class of his own on how to get off the streets.
Meanwhile, for Mandy, who still lives on the streets after losing her job when she got ill from working 14-hour days, the university does something more than just providing a platform for learning - it gives her something to aim for.
"Eventually, I will think of something, which I can do to turn things around," she said.
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