Neither. Both lyrics and chords are out there somewhere waiting to be found. Let me break this down for you with science:

All matter (energy) is neither created nor destroyed. What is music? Sounds? Not necessarily. Music is ENERGY- which is the reason why all of us are intrigued by music and enjoy listening to it. Ever been absolutely encaptured by a live performance and FEEL the energy of it? Music has the ability to make us feel certain ways (I.E. draw out specific emotions). This is because the music creates a certain energy that transfers to the observer. Therefore, all songs ever (times infinity) are already present in the matter that is on earth. You just have to be able to "pick-up" on it when the time is right. Ever hear someone saying something "just came to them"? Ever been with someone and say the same things at the SAME time? Or maybe they say something you were thinking almost to a T? That's because ALL things (tangible, intangible, mentally, and physically) are composed of ENERGY and MATTER. Therefore, all things are already here: they're just waiting to be picked up on by our unconscious/subconscious mind.

On a side note, Chords/progressions usually come to me first BUT sometimes it is the other way around. Channel your inner Chi power.