Through his father's lectures, Christian came under the influence of the political philosophy of Hugo Grotius and Samuel Pufendorf, and continued the study of law at the University of Frankfurt (Oder) in 1675, completing his doctorate in 1679. In 1680, he married Anna Christine Heyland and started a legal practice in Leipzig; the following year he began teaching at the university’s law school as well. In 1684 he became professor of natural law, soon attracting attention by his abilities, and particularly by his attack on traditional prejudices, in theology and jurisprudence.