Hi Psuedonymous. I picked butterflies and fossils (rather than dinky toys or stamps) because collecting them could, but needn't be, related to theorising (about natural science or religion). Also the drive to 'get a full set' probably doesn't apply to songs.

I think for some people who collect enjoyment of the social interaction with people having similar interests is part of the attraction.

I raise it in the connection to Harker because everything he decribes people as doing is given a political interpretation. Collectors who had money and leisure time (a wealthy country parson for example) could simply have done it as a hobby.