Alexander Dyce, A General Glossary to Shakespeare's Works

sympathy “If that thy valour stand on,” RICHARD II, iv. 1. 33 “Aumerle has challenged Bagot with some hesitation, as not being his equal, and therefore one hwom, according to the rules of chivalry, he was not obliged to fight, as a noble life was not to be staked in a duel against a baser. Fitzwater then throws down his gage, a pledge of battle; and tells him that if he stand upon sympathies, that is, upon equality of blood, the combat is now offered him by a man of rank not inferior to his own. Sympathy is an affection incident at once to two subjects. This community of affection implies a likeness or equality of nature, and thence our poet transferred the term to equality of blood” (JOHNSON)