不疾不徐 meaning in Chinese

neither too fast nor too slow; at an appropriate speed

The foggy sky still seemed falling imperceptibly and regularly down on the earth ; the air was still and warm , and there was no sound but now and then the whistle of a huntsman , the snort of a horse , the clack of a whip , or the whine of a dog who had dropped out of his place
雾霭弥漫的天空，仍旧不知不觉地不疾不徐地向地面拉下来天空中一片沉寂，而且和暖，无声无息。有时可以听见猎人的唿哨声，马的响鼻声，或者是离开原地乱走的猎犬刺耳的吠声。