At other times, social relations were explained by the theory of final causes. [794] Whilst everything else exists for the sake of what is endowed with reason, individual beings endowed with reason exist for the sake of each other. Their social connection is therefore a direct natural command. [795] Towards animals we never stand in a position to exercise justice, nor yet towards ourselves. [796] Justice can only be exercised towards other men and towards God. [797] On the combination of individuals and their mutual support rests all their power over nature. A single man by himself would be the most helpless of creatures. [798] The consciousness of this connection between all rational beings finds ample expression in Marcus Aurelius, the last of the Stoics. The possession of reason is, with him, love of society (vi. 14; x. 2). Rational beings can only be treated on a social footing (κοινωνικῶς) (vi. 23), and can only feel happy themselves when working for the community (viii. 7); for all rational beings are related to one another (iii. 4), all form one social unit (πολιτικὸν σύστημα), of which each individual is an integral part (συμπληρωτικός) (ix. 23); one body, of which every individual is an organic member (μέλος) (ii. 1; vii. 13). Hence the social instinct is a primary instinct in man (vii. 55), every manifestation of which contributes, either directly or indirectly, to the good of the whole (ix. 23). Our fellow-men ought to be loved from the heart. They ought to be benefited, not for the sake of outward decency, but because the benefactor is penetrated with the joy of benevolence, and thereby benefits himself. [799] Whatever hinders union with others has a tendency to separate the members from the body, from which all derive their life (viii. 34); and he who estranges himself from one of his fellow-men voluntarily severs himself from the stock of mankind (xi. 8). We shall presently see that the language used by the philosophic emperor is quite in harmony with the Stoic principles. [(2) Justice and mercy.]