The word mizan (pl. mawazin) is derived from the root wazn meaning the knowing of the measure of a thing. It is true that the measure of material things is judged by a pair of scales or by some other implement, but the deeds of man need no scales for their measurement. Raghib writes that by wazn or mizan, in connection with the deeds of men, is meant “the doing of justice in the reckoning of men.” He quotes the following examples: “And the measuring out (wazn) on that day will be just.” (7:8); “And We will set up just balances (mawazin, pl. of mizan) on the day of resurrection” (21:47), where in fact the meaning is made clear in the Koran itself by the addition of the words “no soul shall be dealt with unjustly in the least.” So too elsewhere, a mizan is referred to as working in nature itself: “And the heaven He raised it high, and He made the balance, that you may not be inordinate in respect of the balance, and keep up the measure with equity and do not make the balance deficient” (55:7-9). Here the words used for measure or balance are the same words mizan and wazn. A mizan or balance is first spoken of as existing in connection with the creation of the heavens, and this is followed by an injunction that men should also preserve the balance with equity. Now the balance that is seen working in nature is the law to which every thing is subject, so that, while opposing forces do exist, yet each force is subject to a law and does not nullify the other. Everything works out its destiny according to a measure, and so should man also work out his destiny according to a measure. Hence the injunction not to get inordinate in respect of the measure.
The mizan or balance of men is clearly spoken of elsewhere as having been sent down by God: “We sent Our apostles with clear arguments, and sent down with them the book, and (sent down) the mizan (balance), that men may conduct themselves with equity” (57:25). Now revelation or the book is sent down by God to awaken the spiritual life in a man, and therefore the balance, which is spoken of as having been sent down along with revelation, must also relate to the spiritual life of man. In his physical growth man is undoubtedly subject to the same balance as is the rest of nature, yet apart from that he has a higher life, the spiritual life, which is evolved out of the present life, and the book that is sent with the prophets and the balance both relate to the growth of the spiritual life. The book contains the directions in principle, to do good and shun evil, and the balance is there to weigh the good and the evil, so that the spiritual life awakened in man takes a good or bad turn, a higher or lower form, according to the preponderance of good or evil. Thus not only do good and evil deeds leave their effect behind, but there is also a balance which gives shape to that effect and make the spiritual growth possible, or has a retarding effect on that growth if evil preponderates.
The “balance” of the hereafter, therefore, differs not at all from the “balance” of this life; except that there it takes a more palpable form. The general principle is laid down in the following verses: “And We will set up just balances (mawazin) on the day of resurrection, so no soul shall be dealt with unjustly in the least; and though there be the weight of a grain of mustard seed, We will bring it, and sufficient are We to take account” (21:47)