Ten was, in the opinion of the Pythagoreans, the perfection and consummation of number. The numbers from One to Ten were all that they recognised as primary, original, generative. Numbers greater than ten were compounds and derivatives from the decad. They employed this perfect number not only as a basis on which to erect a bold astronomical hypothesis, but also as a sum total for their list of contraries. Many Hellenic philosophers[42] recognised pairs of opposing attributes as pervading nature, and as the fundamental categories to which the actual varieties of the sensible world might be reduced. While others laid down Hot and Cold, Wet and Dry, as the fundamental contraries, the Pythagoreans adopted a list of ten pairs. 1. Limit and Unlimited; 2. Odd and Even; 3. One and Many; 4. Right and Left; 5. Male and Female; 6. Rest and Motion; 7. Straight and Curve; 8. Light and Darkness; 9. Good and Evil; 10. Square and Oblong.[43] Of these ten pairs, five belong to arithmetic or to geometry, one to mechanics, one to physics, and three to anthropology or ethics. Good and Evil, Regularity and Irregularity, were recognised as alike primordial and indestructible.[44] [Footnote 42: Aristot. Metaphys. [Greek: G]. 2, p. 1004, b. 30. [Greek: ta\ d' o)/nta kai\ tê\n ou)sian o(mologou=sin e)x e)nanti/ôn schedo\n a(/pantes sugkei=sthai.]] [Footnote 43: Aristot. Metaphys. A. 5, p. 986, a. 22. He goes on to say that Alkmæon, a semi-Pythagorean and a younger contemporary of Pythagoras himself, while agreeing in the general principle that "human affairs were generally in pairs," ([Greek: ei)=nai du/o ta\ polla\ tô=n a)nthrôpi/nôn]), laid down pairs of fundamental contraries at random ([Greek: ta\s e)nantio/têtas ta\s tuchou/sas])--black and white, sweet and bitter, good and evil, great and little. All that you can extract from these philosophers is (continues Aristotle) the general axiom, that "contraries are the principia of existing things"--[Greek: o(/ti ta)na/ntia a)rchai\ tô=n o)/ntôn]. This axiom is to be noted as occupying a great place in the minds of the Greek philosophers.] [Footnote 44: Theophrast. Metaphys. 9. Probably the recognition of one dominant antithesis--[Greek: To\ E(/n--ê( a)o/ristos Dua\s]--is the form given by Plato to the Pythagorean doctrine. Eudorus (in Simplikius ad Aristot. Physic. fol. 39) seems to blend the two together.]