Budo as a value of social and spiritual worth evolved from the memory of this period cast into the realities of the Edo shogunate. It has to be understood in terms of both what it revered as lost and what it was dealing with in the age of its development as system of ideas and ideals -- a kind of alchemical transmutation of the practical arts of battle into something else.

As it is framed in the Hagakure:

This is the essence of the Way of the Samurai: you must die anew every morning
and every night. If you continually preserve the state of death in everyday life, you
will understand the essence of Bushido, and you will gain freedom in the Way. Your
whole life will be without blame, and you will succeed in your calling.

What is interesting to me is the parallel of this with western, specifically Christian, teaching on death and rebirth, which was immensely popular in Japan when introduced, so much so that it had to be brutally suppressed by Tokugawa himself as an existential threat to his rule.