"I timed myself and it took me 3 seconds to open a lock. Then I figured out that a baby is born in New York evey 50 seconds, and each person had 18 locks, a new lock is created in New York every 2.777 seconds. So even if all I did was open locks, I'd still be falling behind by .333 locks every second." (41)
Oskar talks a lot and seems to have an odd fascination with locks, keys, and opening locks. This symbolizes his need for privacy, and his interest in the private lives of others.
I actually thought that when Oskar was talking to the locksmith about what company made the key, I think he was just reassuring himself that there are many life adventures and new beginings that could be unlocked by Oskar's key.
"I wrote, "Why was he here?" She said, "For the key." I asked, "What key?" She said, "For the lock." "What lock?" "Don't you know?"" (pg. 279)
keys
I think that locks could represent a prevention from having what we want, or need. Oskar desperately wants to find the lock to the mystery key, but without the lock he is helpless and will never know what the key could possibly mean to his life or what it meant to his father. This can be connected to the search theme. While searching for the lock he also is searching for who he really is, and in addition he is searching for more information about his father and possibly his father's death. Also I think thhe lock is an unknown connection between Oskar and his dad, so Oskar will do anything to have that connection to his dead father who he loved so much.
The motif of locks is significant to the story because it symbolizes Oskar's inability to find the truth, just as a lock prevents people from entering or leaving.