Let only individuals contribute - with sensible limits per election. Otherwise, we are well on our way to ensuring that a government of the moneyed, by the moneyed, and for the moneyed shall not perish from the earth.
But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.