Connecting sociability with arguments about self-interest and natural law, Grotius adopted an account of moral knowledge and motivation for justice that he found in Cicero.For Grotius, sociability serves as a counter to Epicurean views of moral motivation, but it does not by itself provide the grounds of validity of natural law, nor does it alone ground the obligatory force of natural law.Rather, sociability represents an appeal to a basis in human nature for cooperation in the state of nature.Human beings according to Grotius can be motivated to cooperate and adhere to the rules of natural law, but they are not necessarily so motivated.Importantly, Grotius appreciates that sociability creates its own problems, which Grotius believes can be solved by reason alone.For Grotius, the basis of sociability in human nature is not merely instinctual, but also rational; sociability is ultimately based on a respect for the rights to ‘first things’ such as private property, a respect which itself is motivated by right reason.The notion of sociability was to have an important future in the works of later thinkers such as Hobbes, Pufendorf, Shaftesbury, Mandeville, Hutcheson, Hume, Smith and Kant.