Ikkyu Sojun was a Japanese Zen monk and poet who lived in the 15th and 16th centuries. He was known for his unconventional and rebellious nature, as well as his deep understanding and practice of Zen philosophy.

At the core of Ikkyu's philosophy on Zen was the idea of "direct realization." He believed that the ultimate truth or realization could not be found through intellectual understanding or studying scriptures, but only through direct experience and personal realization. This meant that one must go beyond the limitations of the mind and the ego to truly understand Zen.

Ikkyu also emphasized the importance of living in the present moment. He believed that the past and future were merely illusions and that true happiness and peace could only be found in the present. This idea is reflected in his famous poem, "Attention! Attention! Attention! / This alone is the way to enlightenment / Do not be concerned with the past / Or worry about the future / Just be fully present in this moment."

Another key aspect of Ikkyu's philosophy was the rejection of societal norms and conventions. He saw the rigid rules and regulations of society as hindrances to true freedom and enlightenment. He believed in breaking free from societal expectations and living a life of spontaneity and authenticity. This is evident in his famous quote, "The wild and untamed are the only ones who can truly be called human."

Ikkyu also emphasized the importance of simplicity and non-attachment. He believed that one must let go of material possessions and desires in order to find inner peace and contentment. He saw the pursuit of wealth and material possessions as distractions from the true path of Zen.

In addition to these core beliefs, Ikkyu also emphasized the importance of meditation and self-reflection in one's journey towards enlightenment. He believed that through quieting the mind and introspection, one could gain a deeper understanding of the self and the world around them.

In summary, Ikkyu Sojun's philosophy on Zen can be described as a rejection of societal norms and conventions, a focus on living in the present moment, and the importance of direct realization and simplicity. His teachings continue to inspire and guide many in their pursuit of Zen and inner peace.