Situation with memorizing

[.COM]

I have just recently finished learning Chopin's Nocturne Op. 9 No. 2 and the problem is, at least I think it is a problem, is that after I finished learning it, I felt as if I didn't learn it properly because I play the piece by memory rather than looking at the piece and playing it.

If I play the piece by looking at it, I tend to make more mistakes.

What do you all think about this?

[rph108]

I would say look at it while playing it slowly. Its good to have it memorized, but there is a tendecy to forget if you dont look at the music. If you dont think you can do that, use a metrome and turn the speed down as much as is needed to play perfectly. And play in sections if your not.