Definition
A Latin maxim meaning "to compare great things with small things." Used in legal and rhetorical writing to signal that a comparison being drawn is acknowledged to be imperfect or disproportionate — that the writer is measuring something of large significance against something of lesser magnitude, with awareness of the disparity. The phrase functions as a rhetorical concession, not a term of art with operative legal effect. It appears most commonly in judicial opinions, legal treatises, and advocates' arguments when an analogy is offered across a significant difference in scale or importance, and the author wishes to flag the comparison without abandoning it.
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Common Language
The phrase has no meaningful life in ordinary modern English and is not recorded in Wiktionary as a standalone entry. Webster's 1913 does not contain it. It belongs entirely to the Latin rhetorical tradition carried into legal and classical writing.
No gap between common and legal usage requires analysis here; the phrase is pure Latinate legal rhetoric with no parallel in everyday English.
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Why It Matters in Research
This phrase is a navigational challenge because it is not a term of art in the technical sense — it carries no doctrinal content, creates no legal test, and establishes no rule. Researchers encountering it in historical sources should treat it as a rhetorical marker rather than a substantive legal concept.
In corpus research, its significance is primarily stylistic and contextual. When a judge or advocate deploys magna componere parvis, they are signaling analogical reasoning across an acknowledged gap in scale. This matters for two reasons: first, it indicates the argument that follows is comparative and approximate, not identical; second, it can signal that the author is drawing on classical or literary sources (the phrase originates in Virgil's Georgics) rather than legal precedent alone.
Historical legal writing, particularly from the eighteenth and nineteenth centuries, drew heavily on classical Latin maxims as rhetorical ornament and as shorthand for cultivated legal reasoning. Researchers working in that period will encounter such phrases more frequently than in modern sources. Post-twentieth-century opinions and briefs rarely deploy the phrase; its presence in a modern source is itself noteworthy and may indicate unusual rhetorical self-consciousness or direct quotation from an older authority.
The phrase does not vary by jurisdiction and has no statutory or common law definition. It cannot be "applied" or "violated." Researchers should not expect it to appear in headnotes, indexes, or finding aids — it is unlikely to be treated as a searchable legal concept in most databases.
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Historical Dictionary Support
Both Black's Law Dictionary and the Second Edition offer identical, minimal entries: "To compare great things with small things." Neither source elaborates on the phrase's rhetorical function, its origin in Virgil, or the contexts in which it appears in legal writing. This is a case where the historical legal dictionaries function as little more than translation services for Latin readers who did not recognize the phrase.
Neither edition flags the phrase as a maxim of equity, a rule of statutory construction, or a doctrine of any kind. This is accurate. It is a rhetorical convention borrowed from classical literature, and the dictionaries are right not to inflate it. The limitation is that researchers who encounter the phrase in context — where it introduces a significant analogical argument — will find no guidance in the historical sources about what interpretive weight the comparison is meant to carry.
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