The fringe of indetermination which surrounds individuals and the relative, floating and fluid character of individuality itself has often been commented upon (for example, the case of two physical particles whose individuality can no longer be observed when their fields of individuation ordomains of presence encroach upon one another; or the case of the biological distinction between an organ and an organism which depends on the situation of the corresponding intensities according to whether or not these are enveloped within a larger field of individuation).