﴿49﴾ وَمِن كُلِّ شَيْءٍ خَلَقْنَا زَوْجَيْنِ لَعَلَّكُمْ تَذَكَّرُونَ
49. And of everything We have created pairs that you may remember [and take lessons].
The law of parity predominates all things – generation and continuity of life spring from parity. The blessed Verse in question is saying that pairs have been created for each species of creatures forming pairs. “Of everything” designates generality including all species of creatures. Male and female pairs of mankind, animals, and their species are not solely intended by “of everything” as some people might have surmised, but it encompasses all particles and contingent existent beings. It is even a proven fact that the constituent elements, termed prime matter (mādat al-mawād) or element consists of two constituents at times termed positive and negative charges, male and female, and/or energy and matter. In short, the blessed Verse is saying that all contingent existent beings are composite consisting of two things. Unity solely belongs to the Divine Essence of God Almighty Who is Free from parity, elements, or constituents and He is One in His Essence, to His Essence, and in His Essence (“There is no god but Allah”). The blessed Verse indicates that all contingent existent beings consist of constituent elements and any composite being requires a maker; likewise, pairs are in need of each other. Thus, contingent existent beings require the Necessary Being Whose Sacred Presence is devoid of composition, mate, partner, and equal. He is not in need of others in terms of Essence nor is He in need of aids in terms of Acts.
Furthermore, the blessed Qur'anic Verse in question says “of all things,” namely ‘of all existent beings” which may
refer to the fact that all things in the world consist of negative and positive particles. Today, it is a proven fact that atoms consist of different particles including electrons, elementary particles with negative charge, and protons, those with positive charge. It is worthy of note that the dependent clause “that you may remember [and take lessons]” makes a reference to the point that parity, multiplicity, and duality in all things in the world remind man of the point that the Creator of the world is One, since duality is one of the characteristics of created beings.
 For a tradition narrated in this vein from Imam ‘Alī ibn Musā al-RiDā, see Sadūq’s Tawhīd; Nūr al-Thiqalayn, vol. 5, p. 130.