The few persons interested and the small interest fill not the imagination, and engage not the affections.
 David Hume, An Enquiry Concerning the Principles of Morals (1751). copy citation

Context

“but would be no entertainment at all, did not our hearts beat with correspondent movements to those which are described by the historian. Thucydides and Guicciardin support with difficulty our attention; while the former describes the trivial encounters of the small cities of Greece, and the latter the harmless wars of Pisa. The few persons interested and the small interest fill not the imagination, and engage not the affections. The deep distress of the numerous Athenian army before Syracuse; the danger which so nearly threatens Venice; these excite compassion; these move terror and anxiety. The indifferent, uninteresting style of Suetonius, equally with the masterly pencil of Tacitus, may convince us of the cruel depravity of Nero or Tiberius:” source