PSI is the 23rd letter in the Greek alphabet and is the name of Peter Sisseck's (of the coveted Pingus and Flor de Pingus) utopian wine from Ribera del Duero. Peter has sought out the best independent vineyard growers in Ribera and is incentivizing them to improve viticultural practices and shun chemicals, lower yields and practice biodynamics by paying them increasingly for the fruit as they improve. The result is a "give back" to the regional wine that also expresses the "soul" of Ribera.