George Orwell said this quote

“ Suddenly, like a lump of submerged wreckage breaking the surface of water, the thought burst into his mind: 'It doesn't really happen. We imagine it. It is hallucination.' He pushed the thought under instantly. The fallacy was obvious. It presupposed that somewhere or other, outside oneself, there was a 'real' world where 'real' things happened. But how could there be such a world? What knowledge have we of anything, save through our own minds? All happenings are in the mind. Whatever happens in all minds, truly happens. ”