Wikipedia
Sub specie aeternitatis ( Latin for "under the aspect of eternity"), is, from Baruch Spinoza onwards, an honorific expression describing what is universally and eternally true, without any reference to or dependence upon the temporal portions of reality.
In clearer English, sub specie aeternitatis roughly means "from the perspective of the eternal". Even more loosely, the phrase is used to describe an alternative or objective point of view.
Spinoza's "eternal" perspective is reflected in his Ethics (Part V, Prop. XXIII, Scholium), where he treats ethics through a geometric investigation that begins with God and nature and then analyzes human emotions and the human intellect. By proceeding sub specie aeternitatis, Spinoza seeks to arrive at an ethical theory that is as precise as Euclid's Elements. In the history of philosophy, this way of proceeding may be most clearly contrasted with Aristotle's manner of proceeding. Aristotle investigates ethics, physics, and metaphysics separately. In his Ethics and Politics, Aristotle begins from common opinions or common sense about human affairs and attempts to arrive at knowledge; throughout, these investigations are guided by an understanding of the limited precision inherent in any study of human affairs. Similarly in his Physics and Metaphysics, Aristotle begins from what is commonly observed and what previous philosophers have written. Aristotle is less than optimistic about the prospect of arriving at geometric precision in any field other than geometry, though his natural philosophy appears to approach precision more closely than does his political philosophy. Aristotle's methodological differences in his "philosophy of human affairs" and his natural philosophy are grounded in the distinction between what is "better known to us" and things "better known in themselves," or what is "first for us" and what is "first by nature" (discussed, among other places, at Metaphysics Z.3, 1029b3–12), a distinction that is deliberately discarded by Spinoza and other modern philosophers.