De sollertia animalium

The tunny[*](Cf. Aelian, De Natura Animal. ix. 42; Aristotle, Historia Animal. viii. 13 (598 b 25 f.).) is so sensitive to equinox and solstice that it teaches even men themselves without the need of astronomical tables; for wherever it may be when the winter solstice overtakes it, in that same place it stands and stays until the equinox. As for that clever device of the crane,[*](See 967 c supra.) the grasping of the stone by night so that if it falls, she may awake from sleep - how much cleverer, my friend, is the artifice of the dolphin, for whom it is illicit to stand still or to cease from motion.[*](Reiske may have been right in suspecting a trimeter of unknown origin in these words.) For its nature is to be ever active[*](Cf. Aelian, De Natura Animal. xi. 22. The dolphin even nurses its young while in motion; Pliny, Nat. Hist. xi. 235; and cf. Aristotle, Historia Animal. ii. 13 (504 b 21 ff.).): the termination of its life and its movement is one and the same. When it needs sleep, it rises to the surface of the sea and allows itself to sink deeper and deeper on its back, lulled to rest by the swinging motion of the ground swell[*](As it were, the cradle of the deep.) until it touches the bottom. Thus roused, it goes whizzing up, and when it reaches the surface, again goes slack, devising for itself a kind of rest combined

with motion.[*](But see Pliny, Nat. Hist. x. 210, where it is reported that dolphins are actually heard snoring. ) And they say that tunnies do the same thing for the same reason.

Having just a moment ago given you an account of the tunny’s mathematical foreknowledge of the reversal of the sun, of which Aristotle[*](Historia Animal. viii. 13 (598 b 25).) is a witness, I beg you to hear the tale of their arithmetical learning. But first, I swear, I must mention their knowledge of optics, of which Aeschylus[*](Nauck, Trag. Graec. Frag. p. 96, frag. 308; Cf. Aelian, De Natura Animal. ix. 42.) seems not to have been ignorant, for these are his words:

Squinting the left eye like a tunny fish.

They seem, indeed, to have poor sight in one eye. And it is for this reason that when they enter the Black Sea, they hug one bank on the right, and the other[*](See Thompson on Aristotle, Historia Animal. viii. 13 (598 b 19 ff.); Glossary, p. 84; Pliny, Nat. Hist. ix. 50. They follow the opposite shore when returning, thus keeping the same eye towards the land.) when they are going out, it being very prudent and sagacious of them always to entrust the protection of themselves to the better eye. Now since they apparently need arithmetic to preserve their consociation and affection for each other, they have attained such perfection of learning that, since they take great pleasure in feeding and schooling together,[*](Cf. Aristotle, Historia Animal. ix. 2 (610 b 1 f.); Aelian, De Natura Animal. xv. 3, 5.) they always form the school into a cube, making it an altogether solid figure with a surface of six equal plane sides; then they swim on their way preserving their formation, a square that faces both ways. Certainly a hooer[*](A watcher posted on a tall mast to warn fishermen of the approach of a shoal and to give a count. See Thompson on Aristotle, Historia Animal. iv. 10 (537 a 19); Glossary, p. 87; Gow on Theocritus, iii. 26; Mair on Oppian, Hal. iii. 638. Accounts of the ancient tunny fishery are given by Thompson, Glossary, pp. 84-88; Pace, Atti R. Ac. Archeologia Napoli, N.S. xii (1931/2), pp. 326 ff.; and Rhode, Jahrb. f. class. Phil., Suppb. xviii (1900), pp. 1-78. An account of the ancient and the modern tunny fishery is given by Parona, R. Comitato Talasso-grafico Italiano, Memoria, no. 68, 1919.) watching for tunnies who counts the exact number on the surface at once makes known the total number of the shoal, since he knows that the depth is equal one to one with the breadth and the length.