Objection 1. It would seem that the higher angels do not understand by more universal species than the lower angels. For the universal, seemingly, is what is abstracted from particulars. But angels do not understand by species abstracted from things. Therefore it cannot be said that the species of the angelic intellect are more or less universal.
Objection 2. Further, whatever is known in detail is more perfectly known than what is known generically; because to know anything generically is, in a fashion, midway between potentiality and act. If, therefore, the higher angels know by more universal species than the lower, it follows that the higher have a more imperfect knowledge than the lower; which is not befitting.
Objection 3. Further, the same cannot be the proper type of many. But if the higher angel knows various things by one universal form, which the lower angel knows by several special forms, it follows that the higher angel uses one universal form for knowing various things. Therefore he will not be able to have a proper knowledge of each; which seems unbecoming.
On the contrary, Dionysius says (Coel. Hier. xii) that the higher angels have a more universal knowledge than the lower. And in De Causis it is said that the higher angels have more universal forms.
I answer that, For this reason are some things of a more exalted nature, because they are nearer to and more like unto the first, which is God. Now in God the whole plenitude of intellectual knowledge is contained in one thing, that is to say, in the Divine essence, by which God knows all things. This plenitude of knowledge is found in created intellects in a lower manner, and less simply. Consequently it is necessary for the lower intelligences to know by many forms what God knows by one, and by so many forms the more according as the intellect is lower.
Thus the higher the angel is, by so much the fewer species will he be able to apprehend the whole mass of intelligible objects. Therefore his forms must be more universal; each one of them, as it were, extending to more things. An example of this can in some measure be observed in ourselves. For some people there are who cannot grasp an intelligible truth, unless it be explained to them in every part and detail; this comes of their weakness of intellect: while there are others of stronger intellect, who can grasp many things from few.
Reply to Objection 1. It is accidental to the universal to be abstracted from particulars, in so far as the intellect knowing it derives its knowledge from things. But if there be an intellect which does not derive its knowledge from things, the universal which it knows will not be abstracted from things, but in a measure will be pre-existing to them; either according to the order of causality, as the universal ideas of things are in the Word of God; or at least in the order of nature, as the universal ideas of things are in the angelic mind.
Reply to Objection 2. To know anything universally can be taken in two senses. In one way, on the part of the thing known, namely, that only the universal nature of the thing is known. To know a thing thus is something less perfect: for he would have but an imperfect knowledge of a man who only knew him to be an animal. In another way, on the part of the medium of such knowledge. In this way it is more perfect to know a thing in the universal; for the intellect, which by one universal medium can know each of the things which are properly contained in it, is more perfect than one which cannot.
Reply to Objection 3. The same cannot be the proper and adequate type of several things. But if it be eminent, then it can be taken as the proper type and likeness of many. Just as in man, there is a universal prudence with respect to all the acts of the virtues; which can be taken as the proper type and likeness of that prudence which in the lion leads to acts of magnanimity, and in the fox to acts of wariness; and so on of the rest. The Divine essence, on account of Its eminence, is in like fashion taken as the proper type of each thing contained therein: hence each one is likened to It according to its proper type. The same applies to the universal form which is in the mind of the angel, so that, on account of its excellence, many things can be known through it with a proper knowledge.
Source: Summa Theologica (New Advent)