to the strings is most important. For several years, it was thought among the guitar community that Segovia plucked the strings with a combination of fingertip and nail, as stated by Christopher Parkening, but Segovia plucked the strings only with the nails. When asked which technique he used, he replied that it was "the only one there is: nails. Because they bring timbre differences and colour variation and give sonorous volume to the guitar." His right hand was placed so that the nails were perpendicular to the strings. That way, the nail alone would press the string. At the same time, it was thought that was the only way to avoid unpleasant noise coming from the low strings (E, A and D) of the guitar when they were plucked. Segovia created a strong bass sound with his right thumb in spite of his technique, largely because of the flexibility that he had in his thumb, which helped to create a very strong and voluminous sound in the bass notes. Another innovation that separated Segovia from the Tarrega school was the search for the tension in the strings by placing his right hand further to the right side. That way, he could obtain colour variation but also an especially strong, round and voluminous sound, which was very helpful for giving concerts in big halls (the technique was later used by Narciso Yepes). Before Segovia, guitarists from the Tarrega school played the guitar with the hand right over the soundhole and thus created a mellow sound but could not fill the whole space of a large concert hall. After World War II, Segovia became among the first to endorse nylon strings, instead of catgut strings. That advance allowed for greater tonal stability and was the final ingredient in the standardization of the instrument. Repertoire Segovia's repertoire consisted of three principal pillars: first, contemporary works, including concertos and sonatas, usually specifically written for Segovia himself by composers with whom he forged working relationships, notably Federico Moreno Torroba, Federico Mompou, and Joaquín Rodrigo, the Mexican composer Manuel Ponce, the Italian composer Mario Castelnuovo-Tedesco, and the great Brazilian composer Heitor Villa-Lobos; second, transcriptions, usually made by Segovia himself, of classical works originally written for other instruments (e.g., lute, harpsichord, piano, violin, cello) by Johann Sebastian Bach, Isaac Albéniz, Enrique Granados, and many other prominent composers; third, traditional classical guitar works by composers such as Fernando