How do I capture fleeting musical moments before they disappear from my mind?

You need a system that doesn't interrupt the moment itself. For me, it's always pen and paper first—not a phone recording, not notation software. The act of writing by hand, even in rough sketches, keeps you in the interior space where the idea is alive. Write what you hear, not what you think you should write. Abbreviations are fine. A few melodic contours. A chord symbol. The feeling. The texture. Speed matters less than capturing the essential thing before it dissolves. I also keep fragments organized by date and context—what was I doing, what was I observing when this arrived? That metadata becomes surprisingly valuable weeks later when you're reviewing. The real practice is attention itself. The more you genuinely listen—to your own thoughts, to silence, to small sounds—the more frequent and substantial these moments become. They're not rare accidents. They're glimpses of what you're already contemplating at depth. Treat the capture process as part of the composition, not separate from it.