The sexual factor is, however, the simplest and most primitive element of modesty, and may, therefore, be mentioned first. Anyone who watches a bitch, not in heat, when approached by a dog with tail wagging gallantly, may see the beginnings of modesty. When the dog's attentions become a little too marked, the bitch squats firmly down on the front legs and hind quarters though when the period of oestrus comes her modesty may be flung to the air and she eagerly turns her hind quarters to her admirer's nose and elevates her tail high in the air. Her attitude of refusal is equivalent, that is to say, to that which in the human race is typified by the classical example of womanly modesty in the Medicean Venus, who withdraws the pelvis, at the same time holding one hand to guard the pubes, the other to guard the breasts.[9] The essential expression in each case is that of defence of the sexual centers against the undesired advances of the male.[10] Stratz, who criticizes the above statement, argues (with photographs of nude women in illustration) that the normal type of European surprised modesty is shown by an attitude in which the arms are crossed over the breast, the most sexually attractive region, while the thighs are pressed together, one being placed before the other, the shoulder raised and the back slightly curved; occasionally, he adds, the hands may be used to cover the face, and then the crossed arms conceal the breasts. The Medicean Venus, he remarks, is only a pretty woman coquetting with her body. Canova's Venus in the Pitti (who has drapery in front of her, and presses her arms across her breast) being a more accurate rendering of the attitude of modesty. But Stratz admits that when a surprised woman is gazed at for some time, she turns her head away, sinks or closes her eyes, and covers her pubes (or any other part she thinks is being gazed at) with one hand, while with the other she hides her breast or face. This he terms the secondary expression of modesty. (Stratz, _Die Frauenkleidung_, third ed., p. 23.)