One of the fundamental issues dealt with in the Nahj al-balaghah relates to theological and metaphysical problems. In all, there are about forty places in the sermons, letters, and aphorisms where these matters are discussed. Some of these pertain to the aphorisms, but more often the discussion is longer, covering sometimes several pages.
The passages on tawhid (Divine Unity) in the Nahj al-balaghah can perhaps be considered to be the most wonderful discussions of the book. Without any exaggeration, when we take into account the conditions in which they were delivered, they can almost be said to be miraculous.
The discussions on this theme in the Nahj al-balaghah are of a varied nature. Some of them constitute studies of the scheme of creation bearing witness to Divine creativity and wisdom. Here, 'Ali speaks about the whole system of the heaven and the earth, or occasionally discusses the wonderful features of some specific creature like the bat, the peacock or the ant, and the role of Divine design and purpose in their creation. To give an example of this kind of discussion, we may quote a passage regarding the ant:
Have you observed the tiny creatures that He has created? How He has made them strong and perfected their constitution and shaped their organs of hearing and sight, and how He has styled their bones and skin? Observe the ant with its tiny body and delicate form. It is so small that its features can hardly be discerned by the eye and so insignificant that it does not enter our thoughts. See how it roams about upon the ground and arduously collects its livelihood.
It carries the grain to its hole and deposits it in its store. It collects during the summer for the winter and, when winter arrives, it foresees the time to reemerge. Its livelihood is guaranteed and designed according to its built. The Benefactor and the Provider does not forget or forsake it. He does not deprive it, even though it should be in hard and dry stones and rocks. You will be amazed at the delicate intricacy of its wonderful constitution if you investigate the structure of its alimentary canals, its belly, and its eyes and ears which are in its head ... (Sermon 185)
However, most of the discussions about tawhid in the Nahj al-balaghah are rational and philosophical. The rare sublimity of the Nahj al-balaghah becomes manifest in these discourses. In these philosophical and rational discourses of the Nahj al-balaghah on tawhid what constitutes the focus of all arguments is the infinite, absolute and self-sufficing nature of the Divine Essence. In these passages, 'Ali ('a) attains to the heights of eloquence, and none, neither before him nor after him, has approached him in this aspect.
Another issue dealt with is that of the absolute simplicity (al-basatatal-mutlaqah) of the Divine Essence and negation of every kind of multiplicity, divisibility in the Godhead and refutation of separability of the Divine Attributes from the Divine Essence. This theme occurs repeatedly in the Nahj al-balaghah.
Also discussed is a series of other profound problems which had never been touched before him. They are: God being the First while also being the Last; His being simultaneously the Manifest and the Hidden; His priority over time and number, i.e. His pre-eternity is not temporal and His Unity is not numerical;
His Supremacy, Authority, and Self-sufficiency; His Creativeness; that attendance to one affair does not prevent Him from attending to other affairs; the identity of Divine Word and Act; the limited capacity of human reason to comprehend His reality; that gnosis (ma'rifah) is a kind of manifestation (tajalli) of Him upon the intellects, which is different from conception or cognition by the mind; the negation of such categories and qualities as corporeality,
motion, rest, change, place, time, similarity, opposition, partnership, possession of organs or instruments, limitation and number; and a series of other issues which we shall, God willing, mention later and give examples of every one of these. Even a thinker well-versed in the beliefs and views of ancient and modern philosophers would be struck with wonder to see the wide range and scope of the problems propounded in that wonderful book.
An elaborate discussion of the issues raised and dealt with in the Nahj al-balaghah would itself require a voluminous book and cannot be covered in one or two articles. Unavoidably, we shall be brief; but before we commence our brief survey, we are compelled to mention certain points as an introduction to our discussion.