Imam Reza On Divine Unity-part 4

Imam Reza (as) states in His sermon on Divine Unity:
”وَابْتِدَاؤُهُ إِيَّاهُمْ دَلِيلُهُمْ عَلَى أَنْ لا ابْتِدَاءَ لَهُ لِعَجْزِ كُلِّ مُبْتَدَإٍ عَنِ ابْتِدَاءِ غَيْرِهِ“
translation: “That He is their origin [principle] (ibtida’) is proof for them that He has no origin [principle], for none that has an origin [principle] can originate others” [Uyun-al-Akhbar,chapter#11,hadith#51]

Things that exist and possess the light of being [نور وجود] are either necessary in essence [واجب بالذات] or possible in essence [ممکن بالذات ], but that which is possible in essence or contingent is such that it negates both the necessity of existence [وجوب وجود] and the necessity of non-existence [وجوب عدم], inclined neither towards being nor towards non-being [عدم], but oscillating between both in a state of equilibrium ; such an essence is dependent [محتاج] upon an external agent or a cause [علت] for converting the possibility of its existence [امکان وجود] into a necessity and thereby preferring the possibility of existence over the possibility of non-existence [امکان عدم] ; but if everything that exists were to be possible in essence, so nothing would have come into existence because that which is only possible in existence does not begins to exist unless its existence is first rendered necessary by a cause, and the non-existence or the absence of this cause, is the cause of the non-existence of that which is possible in essence ; but the same question is then asked concerning this cause, and if this cause is also only possible in essence then it must also have a cause and so on and so forth but if every member of a causal-series is an effect [معلول] of some other member and hence possible in essence, so this results in an infinite regress [تسلسل], which is impossible, because an infinite causal chain is a composite [مرکب] of numerous parts that are all contingent in essence since each member of the series is an effect of a preceding one, and is therefore dependent upon these parts for its constitution and composition, but that which is dependent upon something contingent or possible in essence is itself also contingent or possible in essence, therefore the infinite causal chain being essentially-contingent could not come into existence without some cause or an external agent ; now this external agent cannot itself be caused because in that case it would itself only be a part of this infinite causal chain like every other member, therefore to assert that a member of this infinite causal series is a cause of the entire series, so this would be tantamount to affirming that the said part is a cause of itself because the series [of which it is being assumed to be the cause] also includes its own cause, and therefore by causing its cause the part would also be causing its own existence, but this is absurd since nothing can be a cause of itself or the cause of its cause as this implies the existence of a thing before it commences to exist, or the priority and the precedence of a thing before itself, which is impossible, since that implies the simultaneous existence and non-existence of a thing. Therefore the cause of the causal series cannot be something contingent in essence and must be Necessary in Itself ; but that which is Necessary in Itself is the cause of all that which exists without itself being caused by any other, and is therefore the First-Cause of all existence, the Principle of all being.