
Now, if we are to put a date on the design we must remember that after the Palazzo Cornaro had been bought on 18 October 1647 and the Gomez family had finally sold on 3 November of the following year (as a result of the eviction threatened by Innocent X in his Brief of 20 October 1647) Lady Olimpia still had to acquire the palazzo on the right of her own. This was much more difficult and the first move was made on 3 March 1648 when she sent a warning to the abbots, demanding their building in accordance with the Gregorian Constitution: clearly, therefore, the design already existed at that date as it would of necessity have had to be included with the legal documents relating to the case. Then, if you bear in mind that it was through Lady Olimpia that Bernini – by some trick or other (and this design may well have been part of his scheme) – managed to depose Borromini, succeed in regaining the favor of Innocent X and, in late 1647 or early 1648, obtain the commission for the great Four Rivers fountain, you will agree with me that Bernini’s lost original for the reorganisation of Lady Olimpia Pamphili’s three palazzi in the Trevi district should be dated to the end of 1647.
You may object that if Bernini had carried out this design he would have finished the Trevi fountain in rather a poor fashion, despite the rocks and Mount Parnassus, because there was so little water. The answer is simple but several factors are involved. Water had always been a problem: Bernini was currently working on the Four Rivers fountain in front of the Pope’s family residence in Piazza Navona, for which Innocent X had given orders in 1645 to divert as many as 150-180 ounces of water from the Trevi . This had solved the problem, at least in the mind of the Pope. In its new position, the Trevi fountain would lose its former importance and in 1667, Alexander VII would have the idea of transferring it to Piazza Colonna. In Bernini’s 1647 design, the fountain had far less water and could no longer be as grandiose as Bernini himself had intended it to be in 1640 and as Salvi would make it 100 years later, in 1744, he had to increase the water supply by linking in more springs. In the meantime, with the decline in its importance and especially the lack of water, the Trevi had to become highly decorative, as befitted its new status uniting the facades of the three buildings then being acquired by Lady Olimpia.
To conclude this extremely long section, I would again like you to remember a very important fact, and that is the celebrated rivalry between Borromini and Bernini, which was so often revealed in their work. If Gian Lorenzo had actually set about reconstructing that façade, the huge and very beautiful pool of his fountain would have completely filled the space between Palazzo Pamphili and Palazzo Carpegna opposite (which is now the Accademia di San Luca). This would have meant demolishing the whole, or at least the majority, of the latter, which at that very time was being built by Borromini. Bernini's Second Design of the Trevi Fountain Home Page...