Refers to people's attachment to the secular and material; Heart refers to people's understanding of Buddhism and Zen, and people must be persistent in secular materials in order to deeply understand Buddhism.
Extended data:
"You should have nothing to live in, only a heart to live in", from the Diamond Sutra. The key is the word "live" and "heart". Living refers to people's nostalgia for the secular and material; Heart refers to people's understanding of Buddhism and Zen. People should have no attachment to worldly things, so that they can deeply understand Buddhism.
Buddhist terminology, from the full name of the Diamond Sutra, is the Diamond Sutra Prajna Paramita Sutra. Also known as heartless. It is similar to the "emptiness is color" in Prajna Heart Sutra. In other words, no matter where you are, this heart can persevere and naturally arise. If the mind is persistent, just like taking root, it can't effectively control everything.
References:
Baidu Encyclopedia-You should have nothing to live in but your heart.