ns　both　in　India　and　Africa　he　was　in　command　against　Brazil　when　the　great　Brazilian　patriot　Olivier　issued　his　ultimatum。　　It　knows　that　on　that　occasion　St。　Clare　with　a　very　small　force　attacked　Olivier　with　a　very　large　one；　and　was　captured　after　heroic　resistance。　　And　it　knows　that　after　his　capture；　and　to　the　abhorrence　of　the　civilised　world；　St。　Clare　was　hanged　on　the　nearest　tree。　　He　was　found　swinging　there　after　the　Brazilians　had　retired；　with　his　broken　sword　hung　round　his　neck。〃　　　　　〃And　that　popular　story　is　untrue？〃　suggested　Flambeau。　　　　　〃No；〃　said　his　friend　quietly；　〃that　story　is　quite　true；　so　far　as　it　goes。〃　　　　　〃Well；　I　think　it　goes　far　enough！〃　said　Flambeau；　〃but　if　the　popular　story　is　true；　what　is　the　mystery？〃　　　　　They　had　passed　many　hundreds　of　grey　and　ghostly　trees　before　the　little　priest　answered。　　Then　he　bit　his　finger　reflectively　and　said：　〃Why；　the　mystery　is　a　mystery　of　psychology。　　Or；　rather；　it　is　a　mystery　of　two　psychologies。　　In　that　Brazilian　business　two　of　the　most　famous　men　of　modern　history　acted　flat　against　their　characters。　　Mind　you；　Olivier　and　St。　Clare　were　both　heroesthe　old　thing；　and　no　mistake；　it　was　like　the　fight　between　Hector　and　Achilles。　　Now；　what　would　you　say　to　an　affair　in　which　Achilles　was　timid　and　Hector　was　treacherous？〃　　　　　〃Go　on；〃　said　the　large　man　impatiently　as　the　other　bit　his　finger　again。　　　　　〃Sir　Arthur　St。　Clare　was　a　soldier　of　the　old　religious　type　the　type　that　saved　us　during　the　Mutiny；〃　continued　Brown。　〃He　was　always　more　for　duty　than　for　dash；　and　with　all　his　personal　courage　was　decidedly　a　prudent　commander；　particularly　indignant　at　any　needless　waste　of　soldiers。　　Yet　in　this　last　battle　he　attempted　something　that　a　baby　could　see　was　absurd。　One　need　not　be　a　strategist　to　see　it　was　as　wild　as　wind；　just　as　one　need　not　be　a　strategist　to　keep　out　of　the　way　of　a　motor…bus。　　Well；　that　is　the　first　mystery；　what　had　become　of　the　English　general's　head？　　The　second　riddle　is；　what　had　become　of　the　Brazilian　general's　heart？　　President　Olivier　might　be　called　a　visionary　or　a　nuisance；　but　even　his　enemies　admitted　that　he　was　magnanimous　to　the　point　of　knight　errantry。　　Almost　every　other　prisoner　he　had　ever　captured　had　been　set　free　or　even　loaded　with　benefits。　　Men　who　had　really　wronged　him　came　away　touched　by　his　simplicity　and　sweetness。　　Why　the　deuce　should　he　diabolically　revenge　himself　only　once　in　his　life；　and　that　for　the　one　particular　blow　that　could　not　have　hurt　him？　Well；　there　you　have　it。　　One　of　the　wisest　men　in　the　world　acted　like　an　idiot　for　no　reason。　　One　of　the　best　men　in　the　world　acted　like　a　fiend　for　no　reason。　　That's　the　long　and　the　short　of　it；　and　I　leave　it　to　you；　my　boy。〃　　　　　〃No；　you　don't；〃　said　the　other　with　a　snort。　　〃I　leave　it　to　you；　and　you　jolly　well　tell　me　all　about　it。〃　　　　　〃Well；〃　resumed　Father　Brown；　〃it's　not　fair　to　say　that　the　public　impression　is　just　what　I've　said；　without　adding　that　two　things　have　happened　since。　　I　can't　say　they　threw　a　new　light；　for　nobody　can　make　sense　of　them。　　But　they　threw　a　new　kind　of　darkness；　they　threw　the　darkness　in　new　directions。　　The　first　was　this。　　The　family　physician　of　the　St。　Clares　quarrelled　with　that　family；　and　began　publishing　a　violent　series　of　articles；　in　which　he　said　that　the　late　general　was　a　religious　maniac；　but　as　far　as　the　tale　went；　this　seemed　to　mean　little　more　than　a　religious　man。　Anyhow；　the　story　fizzled　out。　　Everyone　knew；　of　course；　that　St。　Clare　had　some　of　the　eccentricities　of　puritan　piety。　　The　second　incident　was　much　more　arresting。　　In　the　luckless　and　unsupported　regiment　which　made　that　rash　attempt　at　the　Black　River　there　was　a　certain　Captain　Keith；　who　was　at　that　time　engaged　to　St。　Clare's　daughter；　and　who　afterwards　married　her。　　He　was　one　of　those　who　were　captured　by　Olivier；　and；　like　all　the　rest　except　the　general；　appears　to　have　been　bounteously　treated　and　promptly　set　free。　Some　twenty　years　afterwards　this　man；　then　Lieutenant…Colonel　Keith；　published　a　sort　of　autobiography　called　‘A　British　Officer　in　Burmah　and　Brazil。'　　In　the　place　where　the　reader　looks　eagerly　for　some　account　of　the　mystery　of　St。　Clare's　disaster　may　be　found　the　following　words：　‘Everywhere　else　in　this　book　I　have　narrated　things　exactly　as　they　occurred；　holding　as　I　do　the　old…fashioned　opinion　that　the　glory　of　England　is　old　enough　to　take　care　of　itself。　　The　exception　I　shall　make　is　in　this　matter　of　the　defeat　by　the　Black　River；　and　my　reasons；　though　private；　are　honourable　and　compelling。　　I　will；　however；　add　this　in　justice　to　the　memories　of　two　distinguished　men。　　General　St。　Clare　has　been　accused　of　incapacity　on　this　occasion；　I　can　at　least　testify　that　this　action；　properly　understood；　was　one　of　the　most　brilliant　and　sagacious　of　his　life。　　President　Olivier　by　similar　report　is　charged　with　savage　injustice。　　I　think　it　due　to　the　honour　of　an　enemy　to　say　that　he　acted　on　this　occasion　with　even　more　than　his　characteristic　good　feeling。　To　put　the　matter　popularly；　I　can　assure　my　countrymen　that　St。　Clare　was　by　no　means　such　a　fool　nor　Olivier　such　a　brute　as　he　looked。　　This　is　all　I　have　to　say；　nor　shall　any　earthly　consideration　induce　me　to　add　a　word　to　it。'〃　　　　　A　large　frozen　moon　like　a　lustrous　snowball　began　to　show　through　the　tangle　of　twigs　in　front　of　them；　and　by　its　light　the　narrator　had　been　able　to　refresh　his　memory　of　Captain　Keith's　text　from　a　scrap　of　printed　paper。　　As　he　folded　it　up　and　put　it　back　in　his　pocket　Flambeau　threw　up　his　hand　with　a　French　gesture。　　　　　〃Wait　a　bit；　wait　a　bit；〃　he　cried　excitedly。　　〃I　believe　I　can　guess　it　at　the　first　go。〃　　　　　He　strode　on；　breathing　hard；　his　black　head　and　bull　neck　forward；　like　a　man　winning　a　walking　race。　　The　little　priest；　amused　and　interested；　had　some　trouble　in　trotting　beside　him。　Just　before　them　the　trees　fell　back　a　little　to　left　and　right；　and　the　road　swept　downwards　across　a　clear；　moonlit　valley；　till　it　dived　again　like　a　rabbit　into　the　wall　of　another　wood。　　The　entrance　to　the　farther　forest　looked　small　and　round；　like　the　black　hole　of　a　remote　railway　tunnel。　　But　it　was　within　some　hundred　yards；　and　gaped　like　a　cavern　before　Flambeau　spoke　again。　　　　　〃I've　got　it；〃　he　cried　at　last；　slapping　his　thigh　with　his　great　hand。　　〃Four　minutes'　thinking；　and　I　can　tell　your　whole　story　myself。〃　　　　　〃All　right；〃　assented　his　friend。　　〃You　tell　it。〃　　　　　Flambeau　lifted　his　head；　but　lowered　his　voice。　　〃General　Sir　Arthur　St。　Clare；〃　he　said；　〃came　of　a　family　in　which　madness　was　hereditary；　and　his　whole　aim　was　to　keep　this　from　his　daughter；　and　even；　if　possible；　from　his　future　son…in…law。　　Rightly　or　wrongly；　he　thought　the　final　collapse　was　close；　and　resolved　on　suicide。　　Yet　ordinary　suicide　would　blazon　the　very　idea　he　dreaded。　　As　the　campaign　approached　the　clouds　came　thicker　on　his　brain；　and　at　last　in　a　mad　moment　he　sacrificed　his　public　duty　to　his　private。　　He　rushed　rashly　into　battle；　hoping　to　fall　by　the　first　shot。　　When　he　found　that　he　had　only　attained　capture　and　discredit；　the　sealed　bomb　in　his　brain　burst；　and　he　broke　his　own　sword　and　hanged　himself。〃　　　　　He　stared　firmly　at　the　grey　facade　of　forest　in　front　of　him；　with　the　one　black　gap　in　it；　like　the　mouth　of　the　grave；　into　which　their　path　plunged。　　Perhaps　something　menacing　in　the　road　thus　suddenly　swallowed　reinforced　his　vivid　vision　of　the　tragedy；　for　he　shuddered。　　　　　〃A　horrid　story；〃　he　said。　　　　　〃A　horrid　story；〃　repeated　the　priest　with　bent　head。　　〃But　not　the　real　story。〃　　　　　Then　he　threw　back　his　head　with　a　sort　of　despair　and　cried：　〃Oh；　I　wish　it　had　been。〃　　　　　The　tall　Flambeau　faced　round　and　stared　at　him。　　　　　〃Yours　is　a　clean　story；〃　cried　Father　Brown；　deeply　moved。　〃A　sweet；　pure；　honest　story；　as　open　and　white　as　that　moon。　Madness　and　despair　are　innocent　enough。　　There　are　worse　things；　Flambeau。〃　　　　　Flambeau　looked　up　wildly　at　the　moon　thus　invoked；　and　from　where　he　stood　one　black　tree…bough　curved　across　it　exactly　like　a　devil's　horn。　　　　　〃Fatherfather；〃　cried　Flambeau　with　the　French　gesture　and　stepping　yet　more　rapidly　forward；　〃do　you　mean　it　was　worse　than　that？〃　　　　　〃Worse　than　that；〃　said　Paul　like　a　grave　echo。　　And　they　plunged　into　the　black　cloister　of　the　woodland；　which　ran　by　them　in　a　dim　tapestry　of　trunks；　like　one　of　the　dark　corridors　in　a　dream。　　　　　They　were　soon　in　the　most　secret　entrails　of　the　wood；　and　felt　close　about　them　foliage　that　they　could　not　see；　when　the　priest　said　again：　　　　　〃Where　does　a　wise　man　hide　a　leaf？　　In　the　forest。　　But　what　does　he　do　if　there　is　no　forest？〃　　　　　〃Well；　well；〃　cried　Flambeau　irritably；　〃what　does　he　do？〃　　　　　〃He　grows　a　forest　to　hide　it　in；〃　said　the　priest　in　an　obscure　voice。　　〃A　fearful　sin。〃　　　　　〃Look　here；〃　cried　his　friend　impatiently；　for　the　dark　wood　and　the　dark　saying　got　a　little　on　his　nerves；　will　you　tell　me　this　story　or　not？　　What　other　evidence　is　there　to　go　on？〃　　　　　〃There　are　three　more　bits　of　evidence；〃　said　the　other；　〃that　I　have　dug　up　in　holes　and　corners；　and　I　will　give　them　in　logical　rather　than　chronological　order。　　Fi