[en] Comets, especially those which visit the inner parts of the solar system for the first time ('new' comets), are believed to be the least modified members of the solar system and the ones closest to their primordial condition. Their chemical composition and the similarity of the mass ratio of ices and stony material to that expected in dense cool interstellar clouds make it probable that they originated in such a cloud; their isotopic composition and other arguments make the assumption of an origin in the outer parts of the presolar nebula (PSN), first proposed by Cameron (1977) in connection with his model of the (evolving) presolar nebula, particularly attractive. This is discussed in the paper. (Auth.)