  We study realisations of Lie (super)algebras in Weyl (super)algebras and
connections with minimal representations. The main result is the construction
of small realisations of Lie superalgebras, which we apply for two distinct
purposes. Firstly it naturally introduces, and generalises, the Bessel
operators for Jordan algebras in the study of minimal representations of simple
Lie groups. These have already been applied very successfully by several
authors, however an easy direct explanation for their relevance seemed still to
be missing. Secondly, we work out the theoretical realisation concretely for
the exceptional Lie superalgebra D(2,1;a), giving a useful hands-on
realisation.
