The Master shows the Gate, but it is the Student who has to walk through it.
To show one the Right Direction and Right Path, Oral Instructions from a Master are necessary but Mastery of the Subject only comes from one's own Incessant Self-Cultivation.
There is also a great inspirational story in the Mahabharata of "Ekalavya" (https://en.wikipedia.org/wiki/Ekalavya) who became an exceptional archer through self-training.
Eklavya inspires a life-long learning philosophy and his presence seems to be a celebration for the masses. In this EklavyaParv, the motto is 'You Create Yourself" and the legend of Eklavya is a testimony that is forwarded by many thinkers as well. The discipleship that Eklavya represents is the best for a student and enables one to be the creator of one's own destiny.
Adapting to current times, "The Master" can be a "Good Book" and you can have "Many Masters" but the effort and learning has to happen within the Student.
Source: I self-taught myself Martial Arts (JKD, Karate, Taijiquan) from books when i was young. Decades later when i did join a dojo to study under a Master, i was one of the top students with good skill and power.