This book is about some special types of interpersonal relations – above all about friendship, ritual personal and patron–client relationships – and their connections to the institutional matrix in which they develop.

The most important illustrations of such relations are blood brotherhood and affine relationships of covenanted comradeship or sacrosanct amity initiated through some ritual exchange of personal substance (blood, saliva, semen, etc.) as reported in the Muslim Middle East, in Africa (for instance, among the Zande studied by E.E. Evans-Pritchard), in Caucasian tribes and among North American Indians; practices of ‘fictive’ kinship, as found for instance among slaves of warlike African tribes who were adopted into the lineages of their captors, or in the Japanese practices of adoption of strangers into families (mukoyōshi) and into rural kinship units (dozoku); patterns of ritual kinship, such as the various Christian forms of co–parenthood (compadrazgo, comparaggio, etc.) reported in Latin America, southern Europe, the Balkans, Yugoslavia, and other eastern European settings; patron–client relations as found typically in Latin America, southeast Asia and the Mediterranean areas; ritualised bonds of friendship such as blood-friendship or best' friendship links of some African peoples and cultures of the Pacific such as the Tikopia; and the numerous forms of less formalised friendships reported in many, above all complex, societies in general and modern societies in particular.

These interpersonal relations, although in part seemingly informal, and which in one way or another are found in almost all human societies, are yet very often defined in very articulated symbolic and institutional terms.