The essence of natural law is the assertion that there are objective moral principles which are derived from nature which can be discovered from reason. Besides divine law known only to God or given through scripture, Aquinas determined there was natural law or lex naturalis which is obtained through reason and lex humana or human law. Human law is not a copy of natural law but provides solutions to everyday life because natural law does not provide all or even most of the solutions for everyday life. Aquinas also writes that there is need for human law is to force selfish and evil people to act reasonably. Aquinas also stated that human law must be virtuous, necessary, useful, and clear and for the common good.