The Three Parts of Philosophy and Their Subdivisions — Seneca the Younger, Moral Letters to Lucilius 89.9–89.16, Latin & English

§89.9

Philosophiae tres partes esse dixerunt et maximi et plurimi auctores:¹ moralem, naturalem, rationalem. Prima conponit animum. Secunda rerum naturam scrutatur. Tertia proprietates verborum exigit et structuram et argumentationes, ne pro vero falsa subrepant. Ceterum inventi sunt et qui in pauciora philosophiam et qui in plura diducerent.

The greatest and most numerous authors have said that there are three parts of philosophy: moral, natural, and rational. The first composes the mind. The second investigates the nature of things. The third demands the proper meanings of words, structure, and argumentations, lest false things creep in under the guise of truth. Furthermore, there have been found both those who divide philosophy into fewer parts and those who divide it into more.

§89.10

Quidam ex Peripateticis quartam partem adiecerunt civilem, quia propriam quandam exercitationem desideret et circa aliam materiam occupata sit. Quidam adiecerunt his partem, quam οἰκονομικὴν vocant, administrandae familiaris rei scientiam. Quidam et de generibus vitae locum separaverunt. Nihil autem horum non² in illa parte morali reperietur.

Certain of the Peripatetics added a fourth part, the civil, because it requires a certain proper practice and is occupied with another subject matter. Some added to these the part which they call economic, the knowledge of managing domestic affairs. Some also separated a topic concerning the kinds of life. However, none of these will fail to be found in that moral part.

§89.11

Epicurei duas partes philosophiae putaverunt esse, naturalem atque moralem; rationalem removerunt. Deinde cum ipsis rebus cogerentur³ ambigua secernere, falsa sub specie veri latentia coarguere, ipsi quoque locum, quem de iudicio et regula appellant, alio nomine rationalem induxerunt, sed eum accessionem esse naturalis partis existimant.

The Epicureans thought there were two parts of philosophy, natural and moral; they removed the rational. Then, when they were forced by the very facts to distinguish ambiguities and to expose falsehoods lurking under the appearance of truth, they themselves also introduced, under another name, the rational part, which they call the topic concerning judgment and rule, but they consider it to be an addition to the natural part.

§89.12

Cyrenaici naturalia cum rationalibus sustulerunt et contenti fuerunt moralibus, sed hi quoque quae removent, aliter inducunt. In quinque enim partes moralia dividunt, ut una sit de fugiendis et petendis, altera de adfectibus, tertia de actionibus, quarta de causis, quinta de argumentis. Causae rerum ex naturali parte sunt, argumenta ex rationali. Ariston Chius non tantum supervacuas esse dixit naturalem et rationalem, sed etiam contrarias.

The Cyrenaics abolished natural and rational philosophy and were content with moral philosophy alone, but they too introduce in another way what they remove. For they divide moral philosophy into five parts, so that one is on what is to be avoided and sought, another on affections, a third on actions, a fourth on causes, and a fifth on arguments. The causes of things belong to the natural part, and the arguments to the rational. Ariston of Chios said that the natural and rational are not only superfluous, but even contrary.

§89.13

Moralem quoque, quam solam reliquerat, circumcidit; nam eum locum, qui monitiones continet, sustulit et paedagogi esse dixit, non philosophi, tamquam quidquam aliud sit sapiens quam humani generis paedagogus.

He also cut down the moral part , which alone he had left; for he removed that topic which contains admonitions and said it belonged to the pedagogue, not to the philosopher, as if the wise man were anything other than the pedagogue of the human race.

§89.14

Ergo cum tripertita sit philosophia, moralem eius partem primum incipiamus disponere. Quam in tria rursus dividi placuit, ut prima esset inspectio suum cuique distribuens et aestimans quanto quidque dignum sit,⁴ maxime utilis. Quid enim est tam necessarium quam pretia rebus inponere? Secunda de impetu, de actionibus tertia. Primum enim est, ut quanti quidque sit iudices, secundum, ut impetum ad illa capias ordinatum temperatumque, tertium, ut inter impetum tuum actionemque conveniat, ut in omnibus istis tibi ipse consentias.

Therefore, since philosophy is tripartite, let us first begin to arrange its moral part. This it has pleased to divide again into three, so that the first should be the evaluation which distributes to each his own and estimates how much each thing is worth, which is extremely useful. For what is so necessary as to assign prices to things? The second is on impulse, and the third on actions. For the first is that you judge how much each thing is worth, the second that you take an ordered and tempered impulse toward those things, and the third that there be agreement between your impulse and action, so that in all these you may be in harmony with yourself.

§89.15

Quicquid ex tribus defuit, turbat et cetera. Quid enim prodest inter se aestimata habere omnia,⁵ si sis in impetu nimius? Quid prodest impetus repressisse et habere cupiditates in tua potestate, si in ipsa rerum actione tempora ignores nec scias quando quidque et ubi et quemadmodum agi debeat? Aliud est enim dignitates et pretia rerum nosse, aliud articulos, aliud impetus refrenare et ad agenda ire, non ruere. Tunc ergo vita concors sibi est, ubi actio non destituit impetum, impetus ex dignitate rei cuiusque concipitur proinde remissus vel acrior, prout illa digna est peti.⁶

Whichever of the three is lacking, it disturbs the others as well. For what does it profit to have estimated all things among themselves, if you are excessive in your impulse? What does it profit to have repressed impulses and to have desires under your control, if in the very action of things you are ignorant of the proper times, and do not know when each thing, and where, and how, it ought to be done? For it is one thing to know the worth and prices of things, another to know the critical moments, and another to restrain impulses and go, not rush, to things to be done. Therefore, then life is in harmony with itself, when action does not abandon impulse, and impulse is conceived from the worth of each thing , accordingly moderate or more eager, just as that thing is worthy of being sought.

§89.16

Naturalis pars philosophiae in duo scinditur: corporalia et incorporalia. Utraque dividuntur in suos, ut ita dicam, gradus. Corporum locus in hos primum, in ea quae faciunt et quae ex his gignuntur; gignuntur autem elementa. Ipse de elementis locus, ut quidam putant, simplex est, ut quidam, in materiam et causam omnia moventem et elementa dividitur.

The natural part of philosophy is split into two: corporals and incorporals. Both are divided into their own, so to speak, steps. The topic of bodies is first divided into these: into those things which act and those which are produced from them; and those produced are the elements. The topic concerning the elements itself is either simple, as some think, or, as others think, is divided into matter, the cause that moves all things, and the elements.

Syntax notes6 items

89.9dixerunt et maximi et plurimi auctores
The subject of dixerunt is et maximi et plurimi auctores (both the greatest and most numerous authors). The correlation et... et... connects the two superlative adjectives modifying the noun.
89.10Nihil autem horum non
The double negation nihil... non (nothing... not) functions as a strong affirmation equivalent to "every single one of these." Thus, all of these topics will be found within moral philosophy.
89.11Deinde cum ipsis rebus cogerentur
The conjunction cum is followed by the imperfect subjunctive passive cogerentur (circumstantial/causal clause). ipsis rebus is an ablative of instrument or cause ("by the very facts").
89.14quanto quidque dignum sit
The pronoun quanto is an ablative of price/value governed by the adjective dignum. The clause quanto quidque dignum sit constitutes an indirect question serving as the object of the participle aestimans.
89.15aestimata habere omnia
The verb habere combined with the perfect passive participle aestimata (agreeing with omnia) stresses the maintained status of a completed evaluation.
89.15prout illa digna est peti
The passive infinitive peti depends directly on the adjective digna ("worthy to be sought"). While classical prose often uses a gerundive or supine, this construction mirrors the Greek-style infinitive of specification.

Translated by Gemini 3.5 Flash (published 2026-05-25) · Revision history (3, latest 2026-09-22)

2026-09-22 AI review — source 2
2026-09-21 AI review — source 1

urn:cts:latinLit:phi1017.phi015.humanitext-lat2:89.9-89.16