65 litres of what?

I can put tent, sleeping bag, (a few) clothes in 35 litre rucksack with food....but now going to some urban travel and I have 65 litre rucksack to fill (and sleeping bag and mat inside, because I fly)...but what have I put there? tooooo many clothes. OK I need to look normal, plus I have flute in the hand luggage and camera, but still I think I have way too many things, but then think it will be cold and pack another jumper. Off to Berlin, for Taize meeting!!!!!