Over the course of the next four years, Lowell traveled through France, the Netherlands, Belgium, Italy, Greece, Turkey, Armenia, Persia, and Egypt, down the Nile to Khartoum, through Ethiopia, and ultimately to India. Although the bequest providing for "the maintenance and support of public lectures, to be delivered in Boston, upon philosophy, natural history, the arts and sciences, or any of them, as the trustee shall, from time to time, deem expedient for the promotion of the moral, and intellectual, and physical instruction or education of the citizens of Boston" had been set forth before his departure from Boston, "– in a codicil to his will written "amidst the ruins of Thebes" and, subsequently, in letters written from Egypt, he further amplified his ideas about the trust. Although he expressed a preference for lectures on religion and on topics that would contribute to the material prosperity of the region, he ceded to his trustee discretion to "establish lectures on any subject that, in his opinion, the wants and taste of the age may demand".