Charles S. Peirce held a view of human reason as creative. The objective of this article is to explore more deeply the Peircean conception of imagination, indispensable for the correct functioning of reason. The connection of reason and imagination is necessary in order to be able to interpret the world, to advance towards the truth and to direct our own actions. In this paper I will explain the principal forms in which these faculties interact, and will provide examples taken from the Peircean corpus.