I can't remember which philosopher argued this but there was someone who claimed that we only know that we exist because we know that we can think, therefore we have to assume that everyone around us are not humans as we don't know that they can think.
And to a certain extent it's true. I don't know how other people are actually feeling, what they're actually going through. I know that I hide my emotions from people, and they'd never be able to tell how I was actually feeling or how situations affected me. It made me realise that when someone comes to me with a problem I shouldn't trivialise it immediately and think they're being silly getting upset over something so small because maybe to them this is having a profound effect.
This was just a passing thought, nothing too heavy.
