This is a series of two talks based on upcoming joint work with F. Jahnke, where we establish certain connections between perfectoid geometry and model theory of henselian fields. In the first part, we present a model-theoretic generalization of the Fontaine-Wintenberger theorem. This reveals an abundance of elementary statements whose truth value is transferable between a perfectoid field and its tilt. A key ingredient in the proof is an Ax-Kochen/Ershov principle for perfectoid fields (and generalizations thereof).