rote ▁his ▁ 1 9 3 4 ▁story ▁Tri plan et ary ▁to ▁fit ▁in ▁with ▁the ▁L ens man ▁series . ▁First ▁L ens man ▁was ▁written ▁in ▁ 1 9 5 0 ▁to ▁act ▁as ▁a ▁link ▁between ▁Tri plan et ary ▁and ▁Gal actic ▁Pat rol ▁and ▁finally , ▁in ▁the ▁years ▁up ▁to ▁ 1 9 5 4 , ▁Smith ▁re vised ▁the ▁rest ▁of ▁the ▁series ▁to ▁remove ▁incons isten cies ▁between ▁the ▁original ▁L ens man ▁chron ology ▁and ▁Tri plan et ary . ▁ ▁Plot ▁ ▁The ▁series ▁begins ▁with ▁Tri plan et ary , ▁beginning ▁two ▁billion ▁years ▁before ▁the ▁present ▁time ▁and ▁continu ing ▁into ▁the ▁near ▁future . ▁The ▁universe ▁has ▁no ▁life - forms ▁aside ▁from ▁the ▁ancient ▁Ar is ians , ▁and ▁few ▁plan ets ▁besides ▁the ▁Ar is ians ' ▁native ▁world . ▁The ▁peace ful ▁Ar is ians ▁have ▁for eg one ▁physical ▁skills ▁in ▁order ▁to ▁develop ▁cont empl ative ▁mental ▁power . ▁The ▁underlying ▁assumption ▁for ▁this ▁series , ▁based ▁on ▁theories ▁of ▁stell ar ▁evolution ▁ext ant ▁at ▁the ▁time ▁of ▁the ▁books ' ▁writing , ▁is ▁that ▁plan ets ▁form ▁only ▁rarely , ▁and ▁therefore ▁our ▁First ▁and ▁Second ▁Gal ax ies , ▁with ▁their ▁many ▁bill ions ▁of ▁plan ets , ▁are ▁unique . ▁ ▁The ▁Edd ori ans , ▁a ▁dict atorial , ▁power - h un gry ▁race , ▁come ▁into ▁our ▁universe ▁from ▁an ▁al ien ▁space - time ▁continu um