Usually, we understand that shikantaza is formal practice, and koan practice is more mental practice. But this kind of understanding is not complete. This kind of understanding is the understanding of blind men or Seiko. True practice is not formal practice, or so-called shikantaza, or koan practice. None of those. Those practices are just the practice of to whip the ox. The true practice we mean is true shikantaza, not a shikantaza that is the opposite of koan practice.
Drawing of Jizo by Morikazu Kumagai in the Fall 1985 Wind Bell
—cuke.com/ig for links to the source of the photo. Excerpt from Shunryu Suzuki lecture 68-10-12-B as found on shunryusuzuki.com, edited by PF. Go to instagram.com/cuke_archives for the Instagram version.