There is no truth. There is only perception.

Taken absolutely, that is easy to argue with, since the world does not rearrange itself to match what anyone sees. Taken as a warning it is sharp: every account you hold of a situation arrived through a particular position, mood, and set of interests, your own included. You have access to your view of a thing rather than the thing, which is worth remembering before calling anyone else deluded.

When two people describe the same event differently, resist deciding immediately which one is lying. Ask instead what each of them was standing near. The overlap between the two accounts is usually closer to what happened than either version alone.