I wish I had taken better notes when I was younger, or at least thought about it more, so I could remember what I thought of this as a teenager. Surely for a while I didn't think much, of "Countdown" or the entire album. At the time I hadn't heard much saxophone, hadn't heard much hard bop, hadn't heard all that much jazz (though compared to the general populace I was a veritable expert - this speaks to how difficult it can be to get comfortable with a new genre, and how easy). So it was hard to understand just how much Coltrane's playing pushed at the boundaries - tore them apart - of so many different vocabularies. Saxophone, jazz, rhythm, melody.
It opens with a frantic drum solo from Art Taylor, which I constantly underappreciate, in my head, when I think of the song - probably because of what follows it. But the solo is frantic, quick, jittery, really the only thing that could come before Coltrane's entrance other than complete silence.
And then the solo. It's difficult to follow the notes in even the first phrase, which seems enormous, serpentine, neverending, before it ends briefly (for breath - there being no pause in the ideas). There's a reason Coltrane's playing style was dubbed "sheets of sound" - the notes become almost of one body, a mass of sound from every rapid succession of notes crammed into a single breath. At the time, this was some of the most psychedelic stuff around. It's hard for me to reconcile with later developments in jazz and, more importantly, rock and electronic, which became much more overtly psychedelic; but here (and elsewhere on the album, and throughout his career) Coltrane redefined what counted as music, as acceptable sound. At just the right moments, his solo lines, surging, jabbing, babbling, channelling, strike me far more intensely than any effects-pedal guitar solo or rubbery 303 run. For some people, people who can't stomach the later developments in Coltrane's playing, this is as far out - justifiably so, in a way - as jazz could ever go.
"Countdown" walks a line, though, between traditional and avant-garde, mainstream and alternative, old and new. Like everything on Giant Steps it's intensely melodic, once your idea of melody is melted a little bit by the playing. At first it just seems as if the melodic bits bookend the scales and arpeggios - with barely room to breath between the showy pyrotechnics. Eventually, though, you can begin to hear parts of the melodies popping up everywhere - every few notes, every other note, so often that it's hard to tell what you might be able to class as not being a melody. It is of course acceptable to count the whole damn solo, and just sing it to yourself, even if you miss dozens of the notes you don't even know you're missing.
The structure of the tune, like the melody lines and the rhythms (everything is swung like a mother, though it's hard to tell because there's not much space between the notes), bears witness to the violent consequences of Coltrane's improvisation: to accomodate the solo, the song is basically turned backwards. The drum solo starts it off (though this was somewhat common in bebop, which notably shares a lot of the more avantish qualities of "Countdown" - this being bebop at its most extreme). Then, the solo run. Then, closing it off, what would in a less fantastic bop song be the head, the opening statement of the melody, to later be improvised upon. The name suits the structure, though the explosion at the end of the fast 2:21 is so tightly swung and phrased, it contradicts our usual picture of explosions.