aString := 'Now is the time for all good men to come to the aid of their blah blah blah'.

aString select: [:each | each isVowel].

" --> 'oieieoaooeooeoeaioeiaaa' "

aString reject: [:gobbledy | gobbledy isVowel].

" --> 'Nw s th tm fr ll gd mn t cm t th d f thr blh blh blh'"

aString detect: [:gobbledy | gobbledy isVowel].

" --> $o"