Jaspers considered primary delusions to be ultimately "un-understandable", since he believed no coherent reasoning process existed behind their formation. This view has caused some controversy, and the likes of R. D. Laing and Richard Bentall (1999, p. 133–135) have criticised it, stressing that this stance can lead therapists into the complacency of assuming that because they do not understand a patient, the patient is deluded and further investigation on the part of the therapist will have no effect. For instance Huub Engels (2009) argues that schizophrenic disordered speech may be understandable, just as Emil Kraepelin's dream speech is understandable.