Keys may open multiple doors. Even a single key can open many locks, if constructed in the appropriate way. The obverse of key is also key, at least in the function of keys to lock doors. Hence the trick of the key is its dialectic function (open/close) of access. We practice the functioning of this binary thinking (1= open, 0= closed) several times a day. Even binary thinking can become very complex in case you consider a bunch of keys or organized as a ring of keys. With a plurality of locations or rooms (home, work, leisure) the uncertainty to have the fitting key to the lock in question at your disposable becomes a bit of a puzzle. Here we are, trial and error enter the stage for most of us. Don’t worry, there are digital tools to solve the problem for you, but then the whole issue of trust comes into play more forcefully. Sharing is not only caring, but also daring. Transponders replace keys and passwords have become the new “passe partout”. This leads to the brave new world of encryption as the keyfactor for security. Encryption is key. Are you already encrypting or still turning keys?
Keys are key to understanding as well. Artists in Berlin-Schöneberg combined the portraits of persons and their bundles of keys next to each other. Keys seem to reveal key personality traits of a person. Life course researchers may investigate the “first ownership” of a key to a room, an apartment or the family home as a factor of independence, even freedom to move. Handing over the keys of a car or your home to a significant other may mark looming restrictions due to health issues.
Anyway, what is your favourite key in music? More a fan of serial music or 12-tone music? 
Research Teaching Consulting