Shingon Buddhism, Kukai and Total Exertion

Was flipping through the Works of Kukai and other books on Shingon Buddhism. The founder of Shingon Buddhism, Kukai, was into anatta and total exertion. Sent some excerpts to Thusness and he too said "Yes. Total exertion.", "Yes, Kukai's expression is good."

It should be noted that Li or Ri (理) is better translated as 'Principle' than 'Noumenon'. 

"Although mind is distinguished from form, they share the same nature. Form is mind, mind is forms. They interfuse with one another without difficulty. Therefore, knowing is the objects of knowledge, and the objects, knowing. Knowing is reality, reality knowing."

- Kūkai