اعتنى نحاة العربية بحروف المعاني، وفصّلوا في استعمالاتها، ووضّحوا معانيَها، وخصائصها، ونبّهوا على الفروق بينها، وعقدوا بينها ــ في كثير من الأحيان ــ مقارنات شتى، وفاضلوا بينها. ولمّا كانت الفروق بين هذه الحروف كثيرة، ووجوه هذه المفاضلة متنوّعة، هدفت هذه الدراسة الكشف عن وجه واحد من وجوه هذه المفاضلة في ضوء عبارتهم: هذا أقعد من هذا؛ أي هذا أبلغ من هذا، أو أوغل منه، أو آكد منه في كذا وكذا؛ فسعت إلى بيان ظواهر هذا القعود، وعلله.      ففسرت الدراسة قولهم: إنّ (إِذَا) أَقْعَدُ مِنْ (مَتَى) فِي شَبَهِ الحَرْفِ، وإنّ السِّينَ أَقْعَدُ فِي شَبَهِ غَالِبِ الحُرُوفِ مِنْ (سَوْفَ)، وإنّ (إِذَا) أَقْعَدُ مِنْ (حَيْثُ) فِي الشَّرْطِ، وإنّ (لَا) أَقْعَدُ فِي النَّفْيِ مِنْ (لَنْ)، وإنّ (مَا) أَقْعَدُ فِي شَبَهِ (لَيْسَ) مِنْ (لَا)، وإنّ (إِمَّا) أَقْعَدُ فِي لَفْظِ الشَّكِ مِنْ (أَوْ)، وإنّ (إِلَى) فِي اسْتِعْمَالِهَا لِانْتِهَاءِ الغَايَةِ أَقْعَدُ مِنْ (حَتَّى)، وإنّ (كَأَنَّ) أَقْعَدُ في التشبِيهِ مِنَ الكَافِ، وإنّ (بَلْ) أَقْعَدَ مِنْ (لَكِنْ) فِي حُرُوفِ العَطْفِ، وإنّ (الَّذِي) أَقْعَدَ مِنْ (مَا) فِي الوَصْفِ. Arabic grammarians conducted extensive research on the letters of meaning, substantially elaborated on their uses, clarified their meanings and characteristics, pointed out the differences between them, and often made various comparisons, and differentiated between them. Since the differences among these letters are many, and the aspects of this differentiation are varied, this study aimed to reveal one aspect of this differentiation based on their statements: “this is more grammatical than this"; “this is more eloquent than this", “this is more thorough, or more certain than this in such-and-such". This study seeks to explain these grammaticalization phenomena and their reasons. The study attempted to interpret the Arabic grammarians' conclusions and reasonings: [i:ða] ‘if' is more grammatical than [mata] ‘when' in the semi-letter, the [sa] ‘will' is more grammatical than the majority of the letters of ‘sawfa' ‘will', [i:ða] ‘if' is more grammatical than [ḥaIθu] ‘where'/'as'/'since' in the conditional, [la:] ‘no' is more grammatical than [lan] ‘will not' in negation, [ma:] ‘what ‘ is more grammatical than [la] ‘no' in the likeness of (is not), [Imma] ‘either' is more grammatical in the doubtful form than [ʼaw] ‘or', [ʼilā] ‘to' is more grammatical in its use (as it indicates the end of the goal) than hatta] ‘until'/'till', and  [kaʼanna]  ‘as if' is more grammatical in comparison from [kaf] ‘as'/'like', [bal] ‘but'/‘rather' is more grammatical than [lakinna] ‘but' in the coordination letters, and [allaði] ‘who'/'that' is more grammatical than [ma:] ‘any'/'some' in description.