- The piano is a keyboard instrument that produces sound when pressed on the keys. Most modern pianos have a row of 88 black and white keys: 52 white keys for the notes of the C major scale (C, D, E, F, G, A, and B) and 36 shorter black keys raised above the white keys and set further back, for sharps and flats. This means that the piano can play 88 different pitches (or “notes”), spanning a range of a bit over seven octaves. The black keys are for the “accidentals” (F♯/G♭, G♯/A♭, A♯/B♭, C♯/D♭, and D♯/E♭), which are needed to play in all twelve keys.
- Aztec philosophy (Wikipedia)
Aztec philosophy was a school of philosophy that developed out of Aztec culture. The Aztecs had a well-developed school of philosophy, perhaps the most developed in the Americas and in many ways comparable to Ancient Greek philosophy, even amassing more texts than the ancient Greeks. Aztec cosmology was in some sense dualistic, but exhibited a less common form of it known as dialectical monism. Aztec philosophy also included ethics and aesthetics. It has been asserted that the central question in Aztec philosophy was how people can find stability and balance in an ephemeral world.