How might monarchs react to the ideas of the Enlightenment?

Negatively

Explanation:

Enlightenment ideas were not completely against monarchs but did have problems with the absolute nature of the rule of said monarchs.

Before Enlightenment, monarchs generally ruled as they pleased with the logic being that they had the right to rule from God and so had the right to control the nation as their personal property.

Enlightenment was against this and instead espoused the logic that a monarch was only able to rule due to a social contract signed between them and the people whereby they would be allowed to rule provided they took care of their subjects.

Monarchs reacted to this with negativity because it meant that they had to stop being so selfish with resources and had to share power with the people. As time went on however, and with constant pressure on them, they had to relent and it led to the dissolution of several monarchies in Europe and the transition of others to Constitutional Monarchies.