Matthew and I kept playing Quake for about another 2 hours, and it was getting quite late. Matthew's vision was getting blurred, and I could tell. I also realised for the first time that he didn't see colour the same way I did - he still saw them distinctly, but they were darker and of a higher contrast. I didn't want him to go, but I knw he was tired, so what could I do? He said he'd come back again tomorrow, and we'd do something else.

He left, and I shut down the second machine. As soon as he removed the headset, I lost the image I had been seeing from his eyes, and the monitor program confirmed that he had gone. I found it hard to sleep knowing what we had done, but must have passed out around 3:30am.