Sambhogakaya Buddha is the perpetual one who exists from beginningless beginning to endless end. And Sambhogakaya is the background of Nirmanakaya Buddha, who exists moment after moment with various forms. Nirmanakaya Buddha is the embodiment of Sambhogakaya Buddha. So, Sambhogakaya Buddha gives birth to Nirmanakaya Buddha which exists moment after moment with various forms. That is why we say sentient beings are numberless, and we exist from beginningless beginning to endless end.
Jizo Bosatsu and Kanzeon Bosatsu statues
—cuke.com/ig for links to the source of the photo. Excerpt from Shunryu Suzuki lecture 68-10-00-C as found on shunryusuzuki.com, edited by PF. Go to instagram.com/cuke_archives for the Instagram version.