Sadr Ul-Mota’allihin has referred to his special proof of the Supreme Necessary Being’s unity as the “Celestial demonstration” and then preferred it to the other demonstrations, presented by Avicenna and some other preceding philosophers. While analysing those demonstrations, he considered them incomplete and defective in some ways and in need of correction. Thus, he proposed the corrective approach. The present essay intends to expound that despite the anteriors demonstrations, Avicenna’s needs not to be corrected and has got all elements necessary for proving the unity of the Supreme Necessary Being.