The comparison between Greek and Islamic thoughts, in general, and between Plato's and Farabi's, in particular, can demonstrate, to some extend, the tendency of the former to philosophy and the latter to Shariah although the founders of these philosophers emphasize their considerable common aspects. The epistemology and ontology presented by these two thinkers end in prominence of knowledge in their views. In Plato's thought, knowledge, in terms of theory, results in philosophy whereas in terms of practice, it results in law.
This law constitutes natural law in the reign of the philosopher king and after this period, this is the philosopher who leaves his written law and trains some lawmakers. In Farabi's view, however, knowledge, in terms of theory, results in philosophy as well as knowing Shariah whereas, in terms of practice, it ends in law. Law in the First King era constitutes Divine Nomos that is Sharia, after that era, all affairs will be governed in accordance with figh'h (Islamic jurisprudence), and apparently a faghih (Islamic jurisprudent) does not need philosophy.