In the next place, I attentively examined what I was, and as I observed that I could suppose that I had no body, and that there was no world nor any place in which I might be; but that I could not therefore suppose that I was not; and that, on the contrary, from the very circumstance that I thought to doubt of the truth of other things, it most clearly and certainly followed that I was; while, on the other hand, if I had only ceased to think, although all the other objects which I had ever imagined had been in reality existent, I would have had no reason to believe that I existed; I thence concluded that I was a substance whose whole essence or nature consists only in thinking, and which, that it may exist, has need of no place, nor is dependent on any material thing; so that “I,” that is to say, the mind by which I am what I am, is wholly distinct from the body, and is even more easily known than the latter, and is such, that although the latter were not, it would still continue to be all that it is.

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Piano (Wikipedia) 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.