The purpose of the article is to explain two curious doctrines maintained by frege and rejected by wittgenstein in the 'tractatus logico-philosophicus'. that a special assertion sign is necessary was maintained by frege because he wanted to apply his concept-writing to ordinary language, and it was rejected by wittgenstein because his concern in the 'tractatus' was with scientific assertions only. frege's paradoxical notion that 'the concept horse is not a concept' was a consequence of his symbolizing functions by 'unsaturated' expressions. (...) wittgenstein's picture theory eliminated expressions for relations and thereby avoided the fregean paradox. (shrink)