1 8 5 1 ▁published ▁a ▁significant ▁and ▁philosoph ically ▁sound ▁book ▁on ▁the ▁idea ▁of ▁re inc arn ation , ▁conf essed ▁to ▁being ▁a ▁pup il ▁of ▁' K ern ings '. ▁ ▁The ▁great ▁char is ma ▁of ▁K ern ing ' s ▁deep ening ▁work ▁in ▁Mason ic ▁circles ▁is ▁att ested ▁by ▁a ▁wealth ▁of ▁honor ary ▁certific ates , ▁especially ▁of ▁German ▁lod ges . ▁ ▁Y oga ▁ ▁Kre bs ▁developed ▁a ▁con son ant - v owel - based ▁form ▁of ▁y og ic ▁practice , ▁which ▁was ▁published ▁by ▁his ▁pup il ▁and ▁successor ▁Karl ▁Kol b ▁in ▁" The ▁Reb irth , ▁the ▁Inner ▁True ▁Life " ▁( s ometimes ▁also ▁under ▁the ▁title ▁" The ▁Let ter ▁Book "). ▁These ▁exer cis es , ▁which ▁were ▁focused ▁in ▁the ▁feet ▁on ▁the ▁concentr ated ▁thinking ▁and ▁feeling ▁of ▁sounds , ▁were ▁taken ▁up ▁and ▁further ▁developed ▁by ▁Karl ▁We inf ur ter . ▁ ▁The ▁writer ▁Gustav ▁Mey r ink , ▁whose ▁" occ ult " ▁nov els ▁are ▁known , ▁is ▁said ▁to ▁have ▁been ▁inspired ▁by ▁E ck stein , ▁who ▁pract iced ▁the ▁K ern ing ▁exer cis es ▁for ▁several ▁years , ▁but ▁in ▁ret ros pect ▁expressed ▁himself ▁neg atively ▁about ▁their ▁value , ▁even ▁considered ▁a ▁sp inal ▁disease ▁as ▁a ▁result ▁of ▁these ▁exer cis es . ▁ ▁In ▁ 1 8 9 6 , ▁Carl ▁K ell ner ▁commented ▁that ▁" K re bs