Bankei Yotaku was a Japanese Zen master who lived during the 17th century and is known for his unique and influential teachings. His teachings had a significant impact on the development of modern Zen Buddhism, shaping its philosophy and practices in various ways.

One of the key contributions of Bankei's teachings was his emphasis on the concept of "Unborn Buddha Mind." This concept states that every individual possesses a pure and enlightened mind from birth, and it is only through societal conditioning and attachment to desires that this mind becomes clouded. Bankei believed that by recognizing and tapping into this innate Buddha Mind, one could achieve enlightenment without the need for intense meditation or strict ascetic practices.

This idea challenged the traditional Zen teachings of the time, which placed a strong emphasis on rigorous meditation and strict adherence to rules and rituals. Bankei's teachings opened up a new approach to Zen practice, emphasizing the importance of self-awareness and inner reflection rather than external practices.

Bankei's teachings also had a significant impact on the role of the teacher in Zen Buddhism. He believed that a teacher's role was not to impart knowledge or enlightenment to their students, but rather to guide them in uncovering their own innate Buddha Mind. This approach to teaching is still widely practiced in modern Zen Buddhism, where teachers act as guides rather than authorities.

Furthermore, Bankei's teachings emphasized the importance of living in the present moment and letting go of attachments to the past and future. This idea is closely related to the concept of mindfulness, which has become a central practice in modern Zen Buddhism. By focusing on the present moment and detaching from desires and expectations, one can achieve a state of inner peace and enlightenment.

Bankei's teachings also had a significant impact on the accessibility of Zen Buddhism. He believed that enlightenment was attainable for everyone, regardless of their social status or level of education. This idea challenged the traditional elitist views of Zen, making it more accessible to the general population.

In conclusion, Bankei Yotaku's teachings had a profound impact on the development of modern Zen Buddhism. His emphasis on the innate Buddha Mind, the role of the teacher, living in the present moment, and accessibility of enlightenment continue to shape the philosophy and practices of Zen Buddhism today. His teachings continue to inspire and guide many practitioners on their path towards enlightenment.