Beginner question about notation in piano sonata No. 3

[Stefan van Kessel]

Hi,

in the seventh measure of Beethoven's piano sonata No.3 (op. 2 no.3)
there's a quarter note D starting on the third beat but also a half note
D as part of the C-D chord.

I don't understand what that notation means. Can anybody tell me how
that is supposed to be played?

Sheet music:
http://imslp.org/images/3/37/Beethoven_-_Piano_Sonatas_Lamond_-_3.png
http://www.all-music-sheets.com/images/PianoSonateOp2No3.jpg

Have a nice day,
Stefan v.K.

[Stefan van Kessel]

I got the answer on reddit. In case anybody else is interested:

"You hold the D down through its full two beats, but the quarter note D
is there to show you it is part of the melody, so you as the player can
ensure its conveyed to the audience properly. Chopins Aeolein Harp (sp?
) does this too kinda. Check its sheep music and youll see what im
talking about. Its part of his Prelude Op25, I beleive no 1 or 4.

EDIT: Aeolian Harp Etude, not Prelude. I R Dum. Example I know its a
little hard to see, but you notice that the notes on the down beat are
bigger than the other 16th notes. This is so you "bring them out" from
the others." (posted by 123not-it, http://redd.it/ez4ua)