Article 1, Section 2, Clause 1
Document 3
William Blackstone, Commentaries 1:165--66
17651. As to the qualifications of the electors. The true reason of requiring any qualification, with regard to property, in voters, is to exclude such persons as are in so mean a situation that they are esteemed to have no will of their own. If these persons had votes, they would be tempted to dispose of them under some undue influence or other. This would give a great, an artful, or a wealthy man, a larger share in elections than is consistent with general liberty. If it were probable that every man would give his vote freely, and without influence of any kind, then, upon the true theory and genuine principles of liberty, every member of the community, however poor, should have a vote in electing those delegates, to whose charge is committed the disposal of his property, his liberty, and his life. But, since that can hardly be expected in persons of indigent fortunes, or such as are under the immediate dominion of others, all popular states have been obliged to establish certain qualifications; whereby some, who are suspected to have no will of their own, are excluded from voting, in order to set other individuals, whose wills may be supposed independent, more thoroughly upon a level with each other.
And this constitution of suffrages is framed upon a wiser principle than either of the methods of voting, by centuries, or by tribes, among the Romans. In the method by centuries, instituted by Servius Tullius, it was principally property, and not numbers that turned the scale: in the method by tribes, gradually introduced by the tribunes of the people, numbers only were regarded and property entirely overlooked. Hence the laws passed by the former method had usually too great a tendency to aggrandize the patricians or rich nobles; and those by the latter had too much of a levelling principle. Our constitution steers between the two extremes. Only such as are entirely excluded, as can have no will of their own: there is hardly a free agent to be found, but what is entitled to a vote in some place or other in the kingdom. Nor is comparative wealth, or property, entirely disregarded in elections; for though the richest man has only one vote at one place, yet if his property be at all diffused, he has probably a right to vote at more places than one, and therefore has many representatives. This is the spirit of our constitution: not that I assert it is in fact quite so perfect as I have here endeavoured to describe it; for, if any alteration might be wished or suggested in the present frame of parliaments, it should be in favour of a more complete representation of the people.
The Founders' Constitution
Volume 2, Article 1, Section 2, Clause 1, Document 3
http://press-pubs.uchicago.edu/founders/documents/a1_2_1s3.html
The University of Chicago Press
Blackstone, William. Commentaries on the Laws of England: A Facsimile of the First Edition of 1765--1769. Chicago: University of Chicago Press, 1979.