meaning and substitution of letter (baa) in quran

The grammarians have mentioned fourteen meanings for the letter bā’، which at least in five cases it is applied in substitute for another letter (fī، min، ‘an، ‘alā، ilā). Is this application simply a substitution or a higher purpose is intended by it? It is to be noted that the Qur’ān is Divine Word and His everlasting Sign and it is not possible that in two identical phrases two different letters are used without any purpose، and for example، to regard the use of the letter ilā and bā’ with the verb aḥsan in the phrases wa qad aḥsana bī and wa aḥsin kamā aḥsana ilayk، simply as a variation in expression. Abundantly found in the Holy Qur’ān، this phenomenon has a purpose much higher than merely variation in expression. One of the goals of this substitution is to expand the meaning of the verb، which through inclusion (taḍmīn) causes another meaning than the meaning of the verb itself so that the verb، besides its main meaning، may have other meanings that are achieved by means of being laid next to other letters. In order to better understand the use of this letter، it is necessary to examine various examples of it and to inquire into the meanings obtained from it.