158 THEARCHITECTURE
OF HUMANISM
themainsubstantial,andofwhichtheseriousinterestismanifest,can'carry'acertainmeasureofevidentillusionand,needlesstosay,anindefiniteamountofillusion whichescapesalldetectionsave thatof
theplumb-lineand measure. An entire facadeof false
windowsmaybetheatrical. Asingle suchwindow,
especially whereits practical necessity is for
anyreasonobvious,lowersinnosenseourconfidenceinthe design. Between these extremesthe justifiablelimitsoflicencearediscoverableonly—
^andweredis-covered—
^byexperiment.We:have dweltmerely on afew conspicuousex-amplesofthemoraljudgmentinarchitecture,select-ing fordefencetheworst excessesofthe most 'im-moral'ofthestyles. Themainprincipleinallthesematters
is clear: the aesthetic purposeofthe workdeterminesthemeanstobeemployed. Thatpurposemightconceivably give
aclue tothe natureoftheartist—tohisfundamentaltendenciesofchoice. But
wemustunderstandit
rightly. Themoral
judgment,deceived by a false analogy with conduct, tends
to intervene before the aesthetic
purpose
has beenimpartiallydiscerned.
Anartistmayfailinwhathe
hassetbeforehim,hisfailuremay
beamoralone,arecognisable negligence,
but it is manifested,nonetheless,inanaesthetic
failure,andisonlytobedis-coveredforwhatitisbya
knowledgeofthe
aestheticpurpose. It follows