The article argues for the dialectical relationship between choices in relief mode and the functions of sacred imagery in Renaissance carving, especially that of Desiderio da Settignano. Working out from recent presentations of relief sculpture at exhibition, the case is made for the appeal by Florentine sculptors to touch as a measure of truth. Touch is simultaneously aroused and denied through the staging of subjects representing the body of Christ (with its special ontological status) and through the choice of relief modes that draw attention to different degrees of sacred presence. At the centre is a reading of Desiderio's sacrament tabernacle for San Lorenzo showing how and why Desiderio invented an ‘in-between’ mode that places the devotee in limbo, between the perception of a past event and a timeless icon. Desiderio himself emerges as an in-between figure whose visionary experiments, developing from Donatello, are never fully absorbed by Verrocchio and the next generation of sculptors.