Summa Theologica by Thomas Aquinas
Published 1467 · 227 pages · 92,501 words · about 10 hours at an average pace · Philosophy, Theology, Nonfiction
How hard is Summa Theologica to read?
Summa Theologica scores 86 out of 100 for difficulty on ReadingRate, making it very challenging. The score is a weighted composite of nine measures: four of how hard the prose is to parse, five of how hard the meaning is to extract.
- Vocabulary: 88 out of 100
- Aquinas deploys a systematic scholastic vocabulary drawn from Aristotelian metaphysics and Latin theology — quiddity, esse, essentia, potentia, actus, hypostasis, transubstantiation, synderesis, hylomorphism, consubstantial — that readers must master as a prerequisite to following the arguments. These terms carry precise technical meanings that differ substantially from ordinary English usage. The translation preserves the formal register of medieval disputatio Latin, creating density equivalent to advanced technical philosophy.
- Sentence structure: 82 out of 100
- Each of the 2,669 articles follows a rigid recursive structure: numbered Objections, a Sed contra citing authority, a Respondeo dicendum that develops the primary argument, and numbered Replies to each Objection. Within the Respondeo sections, sentences carry multiple subordinate clauses tracking distinctions between proper and analogical predication, proximate and remote causes, formal and material cause. Readers must hold the content of each objection in memory while processing the Respondeo and its replies. The formal structure aids navigation but demands sustained attention to nested argumentative threads.
- Abstraction: 97 out of 100
- The Summa operates almost entirely at the level of abstract principle and formal distinction. Questions address the existence and attributes of God, the nature of angels as pure intelligences, the metaphysics of being and essence, the psychology of intellect and will, and the structure of divine law — with almost no narrative, sensory scene, or concrete anecdote. Even the ethical sections treat virtues as formal categories rather than behavioral stories. The abstraction level is comparable to Kant's Critique of Pure Reason: readers encounter no concrete world, only conceptual architecture.
- Information density: 95 out of 100
- Each article compresses an entire philosophical debate into a structured unit: objections drawn from Scripture, Aristotle, and the Fathers; a counter-citation; a full argument establishing a position through distinction; and individual rebuttals of each objection. A single page may reference Aristotle's Metaphysics, Augustine's De Trinitate, Pseudo-Dionysius, and Boethius while developing an original argument about the simplicity of God. The density rivals Ulysses in the demands it places on readers' attention, though the demands are philosophical rather than literary.
How Summa Theologica is regarded
Summa Theologica holds a literary regard score of 96 out of 100, weighing its place in the canon, its critical reception, its influence on other writers, and the standing of its author. Regard is measured separately from difficulty: a demanding book is not necessarily an admired one.