Present
- Ahh, we finally figure out what's going on.
- Old Leonard can't make short-term memories, as he explains to Burt. It's a condition called anterograde amnesia.
- He says the last thing can remember is his wife. It seems like a good memory.
- Then Teddy shows up, which we've already seen.
- Okay, so it looks like the black and white scenes are from the past, when his condition was new. These scenes move forward in time.
- The color scenes are taking place what we will call, for simplicity's sake, the present. These scenes are moving backward in time.