Michael Freeden explains this using a metaphor.
Ideologies may be likened to rooms that contain
various units of furniture… If we [enter a room
and] find liberty, rationality, and individualism at
its center, while equality—though in evidence—
decorates the wall, we are looking at an exemplar of
liberalism. If order, authority, and tradition catch
our eye upon opening the door, which equality is
shoved under the bed or, at best, one of its weaker
specimens is displayed only when the guests arrive,
we are looking at a version of conservatism. Core,
adjacent and peripheral units pattern the room and
permit its categorization (Freeden, 1996: 86-7.)