The left hand rests on the neck of the guitar at the first fret with the thumb and index finger. The thumb holding the guitar does not have to be fixed in one place, but it must be able to glide over the neck. In some methods, the authors absolutely forbid students to use the left thumb to press the side of the piano opposite the other fingers, on the 6th string and sometimes on the 5th string. The music is very interesting, it is rich in quality. harmony and four fingers do not have enough time to express the lyrics and bass notes in different tones, so using the thumb is necessary.