Alexander Schmidt, Shakespeare Lexicon and Quotation Dictionary

Strain, subst. 1) effort of thought (as if by violent stretching of the mind): “and, in the publication, make no s., but that Achilles . . . will find Hector's purpose pointing on him,” Troil. I, 3, 326 (== make no difficulty, no doubt).
2) motion of the mind, internal action, impulse, feeling (German: Regung）: other --s of woe, which now seem woe, compared with loss of the<*> will not seem “so,” Sonn. 90, 13. “unless he know some s. in me, that I know not myself, he would never have boarded me in this fury,” Wiv. II, 1, 91. “measure his woe the length and breadth of mine, and let it answer every s. for s., as thus for thus, and such a grief for such,” Ado V, 1, 12. “love is full of unbefitting --s,” LLL V, 2, 770. “if it did infect my blood with joy, or swell my thoughts to any s. of pride,” H4B IV, 5, 171. “do not these high --s of divination in our sister work some touches of remorse?” Troil. II, 2, 113. “can it be that so degenerate a s. as this should once set footing in your generous bosoms?” Troil. II, 2, 113 “thou hast affected the fine --s of honour, to imitate the graces of the gods,” Cor. V, 3, 149. “praise his most vicious s., and call it excellent,” Tim. IV, 3, 213. “it is no act of common passage, but a s. of rareness,” Cymb. III, 4, 95. “O noble s.!” IV, 2, 24.
3) natural disposition: “I would all of the same s. were in the same distress,” Wiv. III, 3, 197. “he is of a noble s., of approved valour and confirmed honesty,” Ado II, 1, 394. “you have shown to-day your valiant s.” Lr. V, 3, 40.
4) stock, race: “he is bred out of that bloody s. that haunted us in our familiar paths,” H5 II, 4, 51. “the s. of man's bred out into baboon and monkey,” Tim. I, 1, 259. “if thou wert the noblest of thy s.” Caes. V, 1, 59. “I do shame to think of what a noble s. you are, and of how coward a spirit,” Per. IV, 3, 24.
5) note, tune, song: “I at each sad s. will strain a tear,” Lucr. 1131. “the s. of strutting chanticleer,” Tp. I, 2, 385. “play false --s,” As IV, 3, 68. “that s. again!” Tw. I, 1, 4. “touch thy instrument a s. or two,” Caes. IV, 3, 257.