Parmenides of Elea was the first of Greek philosophers to analyze in detail what being is. He came to the conclusion that being is without cause, unbegotten, unmovable, and perfect. Being also cannot arise from non-existence, and is indestructible, since change into non-existence is impossible. Such Entity is singular and indivisible, sole, and simple in its ontic status.This concept was developed by Plato, as it emerged that the most important issue was to overcome the aporia of Unity-Plurality. He sought a workaround in the ideal world. On his understanding, only ideas were being, and everything else was a phenomenon (φαινόμενα), or reflections or shadows (σκιαί).This idea of ancient Greek thinkers was thendeveloped by Plotinus, who placed "Oneness" above Being itself. It was the Jewish and Arabic scholars who defended the unity of real Being, identified with the Absolute, and its indivisibility. But these discussions, although related to ontological issues, got pushed into theology. The unity of God was expressed by the famous credo of Israel Shəma 'Yiśrā'êl, which stated that God is eḥad, i.e. one, single, indivisible (Devārīm 6:4). This definition excluded every dualism, pluralism, and trinitarianism. Against this background, there were also disputes with the Catholic theologians, who treated philosophy as a servant of theology. The rejection of such an approach was evident in the views of Joseph Ḳimḥi. Further, a defense of the unity of God appeared in Jacob ben Reuben's writings, and, above all, in those of Moses Maimonides. Considerations on this topic were continued by Arabic thinkers. Surah 112:1 of the Qur'an stated that God is one, unique (Al-Uāḥid), and single, i.e. indivisible (Al-'Aḥad). Therefore God as Absolute is simple ontically – this argument was used by Arabs in defense against dualism and trinitarianism. One of the first Arab thinkers, Wasil ibn Ata, after coming across Greek philosophy maintained that if God is Absolute, then He cannot be limited to any attributes. They are figments of the human mind. Arabic and Persian scholars tried to explain in different ways the relationship between God’s attributes and His essence. Among them were such sages as Al-Ash'ari, Al-Ghazali, Ar-Rumi, Shams i-Tabrizi, Ibn-Rushd, Ibn-Sina, and Ibn-Arabi.They provided a variety of solutions to this problem, thus summarizing the aporia of Unity-Plurality. In general, following Aristotle, consciousness was reduced to the intellect, but the philosophies of Sufi (taṣawwuf) and Kabbalah attempted to surpass the limitations of the mind.Only in Indian philosophy – especially in Advaita-Vedanta – the perfect Self goes beyond what we call the intellect (Greek νους). There, Sat (Being) is the opposite of what is becoming.This perfect Self exists as perfect Being (Sat), Consciousness (Cit), and Happiness (Ānanda). As perfect Being, it is undivided, simple, and only One. All multiplicity is excluded in this Oneness.
