This article integrates theories that explain musical schemata as psychological and statistical associations of features with those that define schemata as collections of cognitively generated archetypes. It is proposed that styles contain a spectrum of features but tend towards congruence. This propensity is thought to originate in cognition and becomes manifest in and between the features of styles. A localised structure, termed the butterfly schema, is argued to be in part a product of the tendency for congruence which is incorporated into the Classical instrumental style. An analysis of the styles and schemata of the Baroque, Classical and Romantic periods explicates their distinct forms of congruent structuring. A survey of European instrumental music of circa 1750–1850 compares the quantity and type of butterfly schemata in samples from the first half of this time period with those from the second. It is found that butterfly schemata with highly congruent features are more common in the earlier, Classical-period samples, suggesting that they are a product of the tendency for congruence in the particular form defined.