The other night, I saw a weird spider on the bathroom mat while I was doing my business. The bathroom was lit only by a night light, so I could barely make it out. It was larger than our usual resident spiders, and writhing around like I had stepped on it and hurt it. I finished, stood up, and turned the light on to see the spider better. It wasn't there. Apparently, spider hallucinations are common.

Several years ago now, I was talking to my girlfriend at the time about an argument we'd had about a week earlier. She listened for a minute and then said, "We never argued about that, where were we?" I told her we were in my car in my garage. She'd not been to my house up to that point. I realized I had dreamt it, but I completely and fully believed it was a real memory, but it simply could not have been. I freaked out for a few days when I read that people often confuse dreams for real memories. I now question which other of my memories are just past dreams. Why would trust any of my memories now, when any number of them might just be old dreams?