Who's "with nature man?" "I?"

Context:

Feuerbach matriculated in the University of Heidelberg with the intention of pursuing a career in the church. Through the influence of Prof. Karl Daub he was led to an interest in the then predominant philosophy of Hegel and, in spite of his father's opposition, enrolled in the University of Berlin in order to study under the master himself. After 22 years, the Hegelian influence began to slacken. Feuerbach became associated with a group known as the Young Hegelians, alternately known as the Left Hegelians, who synthesized a radical offshoot of Hegelian philosophy, interpreting Hegel's dialectic march of spirit through history to mean that existing Western culture and institutional forms—and, in particular, Christianity—would be superseded. "Theology," he wrote to a friend, "I can bring myself to study no more. I long to take nature to my heart, that nature before whose depth the faint-hearted theologian shrinks back; and with nature man, man in his entire quality." These words are a key to Feuerbach's development. He completed his education at Erlangen, at the Friedrich-Alexander-University, Erlangen-Nuremberg with the study of natural science.