Not a preconceived delusion. More like a prelude.
prolusion
n.
5L prolusio, prelude < prolusus, pp. of proludere, to play beforehand < pro3, before + ludere, to play: see PRO32 & LUDICROUS6a preliminary part or performance; often, specif., an introductory essay or article
pro[lu4so[ry 73s! rc8
adj.