Accordingly, the conjurer succeeds in his deception by creating an interest in some unimportant detail, while he is performing the real trick before our eyes without our noticing it. He looks intently at his extended right hand, involuntarily carrying our eyes to the same spot while he is doing the trick with the unobserved left hand. The conjurer's wand is extremely serviceable in directing the spectator's attention to the place where the performer desires to have it.[5] A call upon the attention in one direction prevents its dispersion in another. When engrossed in work, we are oblivious to the noise of the street or even to the knock at the door. An absent-minded person is one so entirely "present-minded" to one train of thought that other stimuli go unperceived. The pickpocket is psychologist enough to know that at the railway station, the theatre, or wherever one's attention is sharply focused in one direction, is he apt to find the psychological moment for the exercise of his pursuit. It is in the negative field of attention that deception effects its purpose. Houdin, the first of the famous prestidigitateurs (died 1871), gives it as one of his rules never to announce beforehand the nature of the effect which you intend to produce, in order that the spectator may not know where to fix his attention. He also tells us that whenever you count "_one_, _two_, _three_," as preliminary to the disappearance of an object, the real vanishing must take place before you say "_three_,"--for the audience have their attention fixed upon "_three_," and whatever is done at "one" or "two" entirely escapes their notice. The "patter" or setting of a trick often constitutes the real art of its execution, because it directs or rather misdirects the attention. When performing before the Arabs, Houdin produced an astounding effect by a very simple trick. Under ordinary circumstances the trick was announced as the changing of the weight of a chest, making it heavy or light at will. The mechanism was simply the attachment and disconnection of an electro-magnet, in those days a far less familiar affair than now. To impress the Arabs he announced that he could spirit a man's strength away and restore it again at a moment's notice. The trick succeeded as usual, but was changed from a mere trick to sorcery--the Arabs declaring him in league with the devil.