The dominant approach to ethics in the fifteenth-century Jesus cult was oriented towards the deep ken. The chapter begins with an overview of what such ethics looked like, and then zooms in on two particular themes, investigating the deep-ken approach to issues of pacifism and vegetarianism. Neither resembles our modern attitudes towards ethics, and deep-ken vegetarianism was only tenuously linked with ethics at all. This century saw related shifts from the deep to the plain ken: from a history that transcended time to a history fractured in the first century and bent once or twice after that, from an ethics based on symbolic consonance to a constructed, articulated ethics, and from a peace based on universal harmony to one based on the actions and emotions of humans. With a focus on Jesus’s Sermon on the Mount and its consequences, this chapter outlines this shift by considering both people committed to non-harm (the Waldensian Poor of Lyon, Nicholas of Hereford, Nicholas of Dresden, Petr Chelčický, Francis of Paola) as well as radical conservatives (Luke of Prague, Erasmus) who took plain-ken paths to more moderate positions.