The Shute Hoyo Shiki says:

“Our own bowing and the Buddhas who are bowed to are all originally within one mind in which there is no bowing and no one to receive it. Although there is no bowing and no one to receive it there is certainly the response of the Buddhas and the receptivity of the ordinary people.”

Shute Hoyo Shiki – Udana-in Nichiki, page 391

For me, bowing when there is no bowing means that all my life is both an expression of gratitude and an attempt to repay the favors I have received. Bowing when there is no one to bow to means that, when I succeed in living according to the principle that all beings possess Buddha nature, then even if people do not seem to respond their lives are forever impacted and the Buddha within them bows. Their receptivity is not dependent upon their knowledge or awareness; the Buddha is always receptive. The one mind of self always abiding in the Lotus Sutra is far reaching and encompassing. The one mind abiding in the Lotus Sutra speaks to the one mind of every being in the universe and so the universe abides in us and bows to us.