So why do you have depression? You have probably puzzled over this many times before. Looked for reasons, triggers behind it.
Perhaps you think you know why; your mum, sister, or other family member has it too. Or maybe it was triggered by a traumatic or upsetting event.
But knowing this doesn’t make the problem go away. Or maybe you can’t think of any reasons to explain it.
But that doesn’t mean there is no cause, because for something to exist it has to have been created. It has to have come from somewhere. And there has to be something maintaining it.