“Somehow, a message had been lost on me. Groups act .
The elements of a group do not have to just sit there,
abstract and implacable; they can do things, they can
‘produce changes.’ In particular, groups arise
naturally as the symmetries of a set with structure.”
— Thomas W. Tucker, review of Lyndon’s Groups and Geometry
in The American Mathematical Monthly , Vol. 94, No. 4
(April 1987), pp. 392-394.
"…groups are invariably best studied through their action on some structure…."
— R. T. Curtis, “Symmetric Generation of the Higman-Sims Group” in
Journal of Algebra 171 (1995), pp. 567-586.
Related material — Other posts now tagged Groups Act.