On May 6, 1912, Abdu'l-Baha was in Cleveland. His talk that night reveals the enthusiasm that remained with Abdu'l-Baha during his entire journey across the U.S. Here are two paragraphs from the talk that he gave that night;
"This is a very joyous evening, an evidence in itself of the possibility of uniting the East and the West—an eastern man appearing before an assemblage of reverent western people. The East and West, the Orient and Occident, shall be united. If we search history, we shall not find the record of such an occasion where one has traveled from the far East to the far West to address a meeting of this universal character. This is a miracle of the twentieth century which proves that the seemingly impossible may become real and possible in the kingdom of man. Praise be to God! The dark ages have disappeared, and the age of light has at last arrived. The Sun of Reality has dawned with supreme effulgence, the realities of things have become manifest and renewed, the mysteries of the unknown have been revealed, and great inventions and discoveries mark this period as a most wonderful age.
Through the ingenuity and inventions of man it is possible to cross the wide oceans, fly through the air and travel in submarine depths. At any moment the Orient and Occident can communicate with each other. Trains speed across the continents. The human voice has been arrested and reproduced, and now man can speak at long distances from any point. These are some of the signs of this glorious century. The great progress mentioned has taken place in the material world. Remarkable signs and evidences have become manifest. Hidden realities and mysteries have been disclosed. This is the time for man to strive and put forth his greatest efforts in spiritual directions. Material civilization has reached an advanced plane, but now there is need of spiritual civilization. Material civilization alone will not satisfy; it cannot meet the conditions and requirements of the present age; its benefits are limited to the world of matter. There is no limitation to the spirit of man, for spirit in itself is progressive, and if the divine civilization be established, the spirit of man will advance. Every developed susceptibility will increase the effectiveness of man. Discoveries of the real will become more and more possible, and the influence of divine guidance will be increasingly recognized. All this is conducive to the divine form of civilization."
The above passage can be found in the book The Promulgation of Universal Peace.