Why is the quality of pity earth-bound while the other two passions are elevating?

Bertrand Russell had three passions governing his life all through. The first two being love and knowledge, which elevated him and took him higher to the heavens that great poets and saints have imagined. However, he said that the third one, i.e., pity, brought him back to the Earth, the reality. The pain in the echoing cries reverberated in his heart. All the sorrow in the wide world forced him to return to the Earth; the children in famine, victims tortured by oppressors, helpless old people that become a hated burden to their children. Russell was moved by the loneliness and poverty and pain that mocked human life. He imagined the ideal life of a human without any suffering and sorrow. So, he longed to alleviate the evil, however, he too suffered. He yet respected the human life and found it worth living and fought throughout his life against all evils. Bertrand fought against the Vietnam war and supported suffragists. Throughout his life he fought in favour of mankind to make this world a better place to live.