electrify　it　by　carrying　out　a　truism。　　They　carry　a　truism　so　faras　in　the　French　Revolution。　　But　exactly　because　Valentin　understood　reason；　he　understood　the　limits　of　reason。　Only　a　man　who　knows　nothing　of　motors　talks　of　motoring　without　petrol；　only　a　man　who　knows　nothing　of　reason　talks　of　reasoning　without　strong；　undisputed　first　principles。　　Here　he　had　no　strong　first　principles。　　Flambeau　had　been　missed　at　Harwich；　and　if　he　was　in　London　at　all；　he　might　be　anything　from　a　tall　tramp　on　Wimbledon　Common　to　a　tall　toast…master　at　the　Hotel　Metropole。　In　such　a　naked　state　of　nescience；　Valentin　had　a　view　and　a　method　of　his　own。　　　　　In　such　cases　he　reckoned　on　the　unforeseen。　　In　such　cases；　when　he　could　not　follow　the　train　of　the　reasonable；　he　coldly　and　carefully　followed　the　train　of　the　unreasonable。　　Instead　of　going　to　the　right　placesbanks；　police　stations；　rendezvous　he　systematically　went　to　the　wrong　places；　knocked　at　every　empty　house；　turned　down　every　cul　de　sac；　went　up　every　lane　blocked　with　rubbish；　went　round　every　crescent　that　led　him　uselessly　out　of　the　way。　　He　defended　this　crazy　course　quite　logically。　　He　said　that　if　one　had　a　clue　this　was　the　worst　way；　but　if　one　had　no　clue　at　all　it　was　the　best；　because　there　was　just　the　chance　that　any　oddity　that　caught　the　eye　of　the　pursuer　might　be　the　same　that　had　caught　the　eye　of　the　pursued。　　Somewhere　a　man　must　begin；　and　it　had　better　be　just　where　another　man　might　stop。　Something　about　that　flight　of　steps　up　to　the　shop；　something　about　the　quietude　and　quaintness　of　the　restaurant；　roused　all　the　detective's　rare　romantic　fancy　and　made　him　resolve　to　strike　at　random。　　He　went　up　the　steps；　and　sitting　down　at　a　table　by　the　window；　asked　for　a　cup　of　black　coffee。　　　　　It　was　half…way　through　the　morning；　and　he　had　not　breakfasted；　the　slight　litter　of　other　breakfasts　stood　about　on　the　table　to　remind　him　of　his　hunger；　and　adding　a　poached　egg　to　his　order；　he　proceeded　musingly　to　shake　some　white　sugar　into　his　coffee；　thinking　all　the　time　about　Flambeau。　　He　remembered　how　Flambeau　had　escaped；　once　by　a　pair　of　nail　scissors；　and　once　by　a　house　on　fire；　once　by　having　to　pay　for　an　unstamped　letter；　and　once　by　getting　people　to　look　through　a　telescope　at　a　comet　that　might　destroy　the　world。　　He　thought　his　detective　brain　as　good　as　the　criminal's；　which　was　true。　　But　he　fully　realised　the　disadvantage。　　〃The　criminal　is　the　creative　artist；　the　detective　only　the　critic；〃　he　said　with　a　sour　smile；　and　lifted　his　coffee　cup　to　his　lips　slowly；　and　put　it　down　very　quickly。　　He　had　put　salt　in　it。　　　　　He　looked　at　the　vessel　from　which　the　silvery　powder　had　come；　it　was　certainly　a　sugar…basin；　as　unmistakably　meant　for　sugar　as　a　champagne…bottle　for　champagne。　　He　wondered　why　they　should　keep　salt　in　it。　　He　looked　to　see　if　there　were　any　more　orthodox　vessels。　　Yes；　there　were　two　salt…cellars　quite　full。　Perhaps　there　was　some　speciality　in　the　condiment　in　the　salt…cellars。　　He　tasted　it；　it　was　sugar。　　Then　he　looked　round　at　the　restaurant　with　a　refreshed　air　of　interest；　to　see　if　there　were　any　other　traces　of　that　singular　artistic　taste　which　puts　the　sugar　in　the　salt…cellars　and　the　salt　in　the　sugar…basin。　Except　for　an　odd　splash　of　some　dark　fluid　on　one　of　the　white…papered　walls；　the　whole　place　appeared　neat；　cheerful　and　ordinary。　　He　rang　the　bell　for　the　waiter。　　　　　When　that　official　hurried　up；　fuzzy…haired　and　somewhat　blear…eyed　at　that　early　hour；　the　detective　（who　was　not　without　an　appreciation　of　the　simpler　forms　of　humour）　asked　him　to　taste　the　sugar　and　see　if　it　was　up　to　the　high　reputation　of　the　hotel。　The　result　was　that　the　waiter　yawned　suddenly　and　woke　up。　　　　　〃Do　you　play　this　delicate　joke　on　your　customers　every　morning？〃　inquired　Valentin。　　〃Does　changing　the　salt　and　sugar　never　pall　on　you　as　a　jest？〃　　　　　The　waiter；　when　this　irony　grew　clearer；　stammeringly　assured　him　that　the　establishment　had　certainly　no　such　intention；　it　must　be　a　most　curious　mistake。　　He　picked　up　the　sugar…basin　and　looked　at　it；　he　picked　up　the　salt…cellar　and　looked　at　that；　his　face　growing　more　and　more　bewildered。　　At　last　he　abruptly　excused　himself；　and　hurrying　away；　returned　in　a　few　seconds　with　the　proprietor。　　The　proprietor　also　examined　the　sugar…basin　and　then　the　salt…cellar；　the　proprietor　also　looked　bewildered。　　　　　Suddenly　the　waiter　seemed　to　grow　inarticulate　with　a　rush　of　words。　　　　　〃I　zink；〃　he　stuttered　eagerly；　〃I　zink　it　is　those　two　clergy…men。〃　　　　　〃What　two　clergymen？〃　　　　　〃The　two　clergymen；〃　said　the　waiter；　〃that　threw　soup　at　the　wall。〃　　　　　〃Threw　soup　at　the　wall？〃　repeated　Valentin；　feeling　sure　this　must　be　some　singular　Italian　metaphor。　　　　　〃Yes；　yes；〃　said　the　attendant　excitedly；　and　pointed　at　the　dark　splash　on　the　white　paper；　〃threw　it　over　there　on　the　wall。〃　　　　　Valentin　looked　his　query　at　the　proprietor；　who　came　to　his　rescue　with　fuller　reports。　　　　　〃Yes；　sir；〃　he　said；　〃it's　quite　true；　though　I　don't　suppose　it　has　anything　to　do　with　the　sugar　and　salt。　　Two　clergymen　came　in　and　drank　soup　here　very　early；　as　soon　as　the　shutters　were　taken　down。　　They　were　both　very　quiet；　respectable　people；　one　of　them　paid　the　bill　and　went　out；　the　other；　who　seemed　a　slower　coach　altogether；　was　some　minutes　longer　getting　his　things　together。　　But　he　went　at　last。　　Only；　the　instant　before　he　stepped　into　the　street　he　deliberately　picked　up　his　cup；　which　he　had　only　half　emptied；　and　threw　the　soup　slap　on　the　wall。　　I　was　in　the　back　room　myself；　and　so　was　the　waiter；　so　I　could　only　rush　out　in　time　to　find　the　wall　splashed　and　the　shop　empty。　　It　don't　do　any　particular　damage；　but　it　was　confounded　cheek；　and　I　tried　to　catch　the　men　in　the　street。　　They　were　too　far　off　though；　I　only　noticed　they　went　round　the　next　corner　into　Carstairs　Street。〃　　　　　The　detective　was　on　his　feet；　hat　settled　and　stick　in　hand。　He　had　already　decided　that　in　the　universal　darkness　of　his　mind　he　could　only　follow　the　first　odd　finger　that　pointed；　and　this　finger　was　odd　enough。　　Paying　his　bill　and　clashing　the　glass　doors　behind　him；　he　was　soon　swinging　round　into　the　other　street。　　　　　It　was　fortunate　that　even　in　such　fevered　moments　his　eye　was　cool　and　quick。　　Something　in　a　shop…front　went　by　him　like　a　mere　flash；　yet　he　went　back　to　look　at　it。　　The　shop　was　a　popular　greengrocer　and　fruiterer's；　an　array　of　goods　set　out　in　the　open　air　and　plainly　ticketed　with　their　names　and　prices。　　In　the　two　most　prominent　compartments　were　two　heaps；　of　oranges　and　of　nuts　respectively。　　On　the　heap　of　nuts　lay　a　scrap　of　cardboard；　on　which　was　written　in　bold；　blue　chalk；　〃Best　tangerine　oranges；　two　a　penny。〃　　On　the　oranges　was　the　equally　clear　and　exact　description；　〃Finest　Brazil　nuts；　4d。　a　lb。〃　　M。　Valentin　looked　at　these　two　placards　and　fancied　he　had　met　this　highly　subtle　form　of　humour　before；　and　that　somewhat　recently。　　He　drew　the　attention　of　the　red…faced　fruiterer；　who　was　looking　rather　sullenly　up　and　down　the　street；　to　this　inaccuracy　in　his　advertisements。　　The　fruiterer　said　nothing；　but　sharply　put　each　card　into　its　proper　place。　　The　detective；　leaning　elegantly　on　his　walking…cane；　continued　to　scrutinise　the　shop。　　At　last　he　said；　〃Pray　excuse　my　apparent　irrelevance；　my　good　sir；　but　I　should　like　to　ask　you　a　question　in　experimental　psychology　and　the　association　of　ideas。〃　　　　　The　red…faced　shopman　regarded　him　with　an　eye　of　menace；　but　he　continued　gaily；　swinging　his　cane；　〃Why；〃　he　pursued；　〃why　are　two　tickets　wrongly　placed　in　a　greengrocer's　shop　like　a　shovel　hat　that　has　come　to　London　for　a　holiday？　　Or；　in　case　I　do　not　make　myself　clear；　what　is　the　mystical　association　which　connects　the　idea　of　nuts　marked　as　oranges　with　the　idea　of　two　clergymen；　one　tall　and　the　other　short？〃　　　　　The　eyes　of　the　tradesman　stood　out　of　his　head　like　a　snail's；　he　really　seemed　for　an　instant　likely　to　fling　himself　upon　the　stranger。　　At　last　he　stammered　angrily：　〃I　don't　know　what　you　'ave　to　do　with　it；　but　if　you're　one　of　their　friends；　you　can　tell　'em　from　me　that　I'll　knock　their　silly　'eads　off；　parsons　or　no　parsons；　if　they　upset　my　apples　again。〃　　　　　〃Indeed？〃　asked　the　detective；　with　great　sympathy。　　〃Did　they　upset　your　apples？〃　　　　　〃One　of　'em　did；〃　said　the　heated　shopman；　〃rolled　'em　all　over　the　street。　　I'd　'ave　caught　the　fool　but　for　havin'　to　pick　'em　up。〃　　　　　〃Which　way　did　these　parsons　go？〃　asked　Valentin。　　　　　〃Up　that　second　road　on　the　left…hand　side；　and　then　across　the　square；〃　said　the　other　promptly。　　　　　〃Thanks；〃　replied　Valentin；　and　vanished　like　a　fairy。　　On　the　other　side　of　the　second　square　he　found　a　policeman；　and　said：　〃This　is　urgent；　constable；　have　you　seen　two　clergymen　in　shovel　hats？〃　　　　　The　policeman　began　to　chuckle　heavily。　　〃I　'ave；　sir；　and　if　you　arst　me；　one　of　'em　was　drunk。　　He　stood　in　the　middle　of　the　road　that　bewildered　that〃　　　　　〃Which　way　did　they　go？〃　snapped　Valentin。　　　　　〃They　took　one　of　them　yellow　buses　over　there；〃　answered　the　man；　〃them　that　go　to　Hampstead。〃　　　　　Valentin　produced　his　official　card　and　said　very　rapidly：　〃Call　up　two　of　yo