DuringtheseexperimentsWoolahadbeenstandingatmysidegazingintentlyatthedoor，andasmyglancefelluponhimitoccurredtometotestthecorrectnessofmyhypothesis，thatthisportalhadbeenthemeansofingresstothetempleusedbyThurid，theblackdator，andMataiShang，FatherofTherns。
Turningawayabruptly，Icalledtohimtofollowme。Foramomenthehesitated，andthenleapedafterme，whiningandtuggingatmyharnesstodrawmeback。Iwalkedon，however，somedistancefromthedoorbeforeIlethimhavehisway，thatImightseepreciselywhathewoulddo。ThenIpermittedhimtoleadmewhereverhewould。
Straightbacktothatbafflingportalhedraggedme，againtakinguphispositionfacingtheblankstone，gazingstraightatitsshiningsurface。ForanhourIworkedtosolvethemysteryofthecombinationthatwouldopenthewaybeforeme。
CarefullyIrecalledeverycircumstanceofmypursuitofThurid，andmyconclusionwasidenticalwithmyoriginalbelief——thatThuridhadcomethiswaywithoutotherassistancethanhisownknowledgeandpassedthroughthedoorthatbarredmyprogress，unaidedfromwithin。Buthowhadheaccomplishedit？
IrecalledtheincidentoftheChamberofMysteryintheGoldenCliffsthattimeIhadfreedThuviaofPtarthfromthedungeonofthetherns，andshehadtakenaslender，needle—likekeyfromthekeyringofherdeadjailertoopenthedoorleadingbackintotheChamberofMysterywhereTarsTarkasfoughtforhislifewiththegreatbanths。Suchatinykeyholeasnowdefiedmehadopenedthewaytotheintricatelockinthatotherdoor。