Satie and his instructions
Satie is as famous for his cheeky, absurd, and even meaningless musical instructions as for his music.
Regarding the Gnossiennes specifically, Markus Lajunen writes as good a description/explanation as I've found:
Satie was famous for mischievous comments. Over the years he included all kinds of written remarks to his compositions e.g. “To whom it may concern: 'I forbid anyone to read the text aloud during the musical performance. Ignorance of my instructions will incur my righteous indignation against the
presumptuous culprit. No exception will be allowed.'”....
By the time Satie composed the Gnossiennes in the late 1800s, he was involved in esoteric gnostic religious sects and movements e.g. Rosicrucianism. These religious movements emphasize secret knowledge that is revealed only for a few selected persons. These ideas might have influenced the way Satie composed the Gnossiennes.
After years of heavy drinking (including Absinth [hallucinogens, anyway? -Aaron]), Satie died in 1925 from cirrhosis of the liver.1
For those of seeking literal/musical meaning in the instructions, it's a dubious project. Nevertheless...
From the Murray Baylor edition of "3 Gymnopedies & 3 Gnossiennes" (Alfred Masterworks, 1993):
- très luisant: "Very radiant".
- questionnez: "Ask!".
- du bout de la pensée: "Deep in thought".
- postulez en vous-même: "Make demands on yourself".
- pas à pas: "Step by step".
- sur la langue: "On the tip of the tongue".
I should preface by saying I interpret the piece based without regard to those instructions. That said, here's what they mean to me, and these meanings are consistent with how I tend to play the piece.
- très luisant: Play with pride. Short of maestoso, but in that realm, giving a bell-like quality to the melody notes. Allow for larger, comparatively more spacious physical movements between bass notes and chords in the left hand.
- questionnez: Allow for some rubato here. Stretch the eighth notes heading up to the topmost B, and give some stress to the half notes, as though there is urgency in finding an answer to whatever the question is.
- du bout de la pensée: Play softer and with a less-than-full tone; just barely touch the key bed. Consider using the una corda pedal.
- postulez en vous-même: This is very much like the questionnez section, except more so. It should sound like each note requires an effort. So a more pronounced stretching of the time in the eighth notes leading up to the B, and a more laborious left hand. As in the très luisant section, putting a sense of effort in the left hand's movements between notes can help reinforce the musical effect.
- pas à pas: Play a bit pedantically. Tempo is strict, little if any dynamic change, play a bit mechanically — as though each note is separate from the next.
- sur la langue: Similar to the du bout de la pensée section, but even softer, gentler, as though the sound is coming from very far away. Una corda pedal is again a possibility here. Slow down, as though you're really trying hard to grasp an idea that's just out of reach, but with each note you're trying to reach a bit further (i.e., requires a bit more time).
1Markus Lajunen is teacher of Theory of Knowledge And Psychology at Jyväskylä Lyceum High School in Finland. His class notes from which I've quoted can be found at link to class notes. Wikipedia says much the same things.