The Wealth of Nations by Part 5 Chapter 1 Page 99

likely method, it was found, of keeping it in constant repair was to make a present of the tolls to Riquet the engineer, who planned and conducted the work.

Those tolls constitute at present a very large estate to the different branches of the family of that gentleman, who have, therefore, a great interest to keep the work in constant repair. But had those tolls been put under the management of commissioners, who had no such interest, they might perhaps have been dissipated in ornamental and unnecessary expenses, while the most essential parts of the work were allowed to go to ruin.

The tolls for the maintenance of a high road cannot with any safety be made the property of private persons. A high road, though entirely neglected, does not become altogether impassable, though a canal does.