– 3 2 9 ). ▁ ▁Tr init arian ▁the ology ▁While ▁at ▁the ▁Greg or ian ▁University , ▁L on er gan ▁composed ▁a ▁two - volume ▁Latin ▁text book , ▁De ▁De o ▁Tr ino ▁( third ▁edition , ▁ 1 9 6 4 ). ▁It ▁has ▁recently ▁appeared ▁in ▁the ▁Collect ed ▁Works ▁together ▁with ▁an ▁inter leaf ▁English ▁translation ▁under ▁the ▁title ▁The ▁Tri une ▁God : ▁Do ctr ines ▁( 2 0 0 9 ) ▁and ▁The ▁Tri une ▁God : ▁System at ics ▁( 2 0 0 7 ). ▁ ▁In ▁The ▁Tri une ▁God : ▁Do ctr ines , ▁L on er gan ▁begins ▁with ▁an ▁exam ination ▁of ▁the ▁dialect ical ▁process ▁by ▁which ▁the ▁dog ma ▁of ▁the ▁Tr inity ▁developed ▁in ▁the ▁first ▁four ▁centuries . ▁This ▁section ▁was ▁previously ▁published ▁in ▁English ▁as ▁The ▁Way ▁to ▁Nice a . ▁The ▁second ▁section ▁of ▁the ▁work ▁adv ances ▁dog m atic ▁th eses ▁on ▁( 1 ) ▁the ▁cons ub st ant ial ity ▁of ▁the ▁Son ▁with ▁the ▁Father , ▁( 2 ) ▁the ▁div inity ▁of ▁the ▁Holy ▁Spirit , ▁( 3 ) ▁the ▁distinction ▁of ▁the ▁divine ▁persons ▁by ▁relations ▁of ▁origin , ▁and ▁( 4 ) ▁the ▁process ion ▁of ▁the ▁Holy ▁Spirit ▁from ▁the ▁Father ▁and ▁the ▁Son ▁( the ▁Fil io que ). ▁The ▁fifth ▁and ▁final ▁th esis ▁is ▁that ▁the ▁Tr inity ▁is ▁a ▁the ological ▁mystery ▁in ▁the ▁strict ▁sense ▁and ▁can ▁only ▁be