Did Tatian write his gospel in Greek or Syriac? Treatments of this most beleaguered crux in Diatessaronic studies have largely depended on a now defunct approach to the source material. The ‘New Perspective’ on Tatian's Diatessaron wants for a new study of this old question. A problematic arrangement of textual data at Luke 19.4 offers unrecognised evidence that Tatian composed in Greek – namely, contradictory testimonia to the Syriac word for Zacchaeus’ ‘sycamore’ in Tatian's gospel reflect different etymological translations of a distinctive, Greek textual variant.