The Jewish High Priest during the Second Temple period, Simeon the Just also termed “the Righteous” because of the piety of his life and his benevolence toward his compatriots, was deeply interested in the spiritual and material development of the nation.
As a high priest of the Great Synagogue he used to say:
“The world exists through three things: the Law, Service (Temple sacrifice, and today prayer), and acts of loving kindness.”
Torah signifies divine revelation; either the fact of communion between God and man, or the wisdom so imparted. Though to Israel alone the Torah was given, yet Israel in this was representative of humanity. Intercourse between God and man is fundamental, and without it human life above the merely animal stage would be impossible.
The service; this is the service in the temple, regarded as the worship of God in the manner appointed by him. If one special element in the service be intended, that may be the sacrifices, as a symbol of obedience to the divine commands, or the priesthood as the appointed agency for performing the service.
Maimonides interprets the word in the former sense, and this lends itself better to generalisation. ‘Deeds of kindness’, denote unselfish beneficence in the fullest measure, to cover any good that one person can do to another.
The ‘three things’ which are declared to be fundamental in human life are thus found to be Revelation, obedience to God, and brotherly love. It is possible however that the second term ‘the service’ was intended to symbolise worship as a fundamental in human life, including in its meaning both obedience to divine precepts, and the functions of consecrated ministers. The saying is only true when thus generalised; but it would be hard to say how much of that more general meaning was present to the mind of Simeon when he uttered it.
~ Pirke Aboth, Sayings of the Fathers, 1:2 (Herford)