Primary sources in philosophy are most frequently the works of the philosopher him/herself, though letters, lectures, and contemporary criticism may also be useful primary materials depending on your exact interest.
Primary sources--such as original documents, essays, letters, diaries, interviews, works of art, and oral histories, can often be found collected in print volumes. Tisch Library has a wide array of print primary sources in its collection. Below is a sample of some of the resources that you can find but remember, this is only a sample, so use JumboSearch to find more or Ask a Librarian for help!
While Tisch Library's collection contains many print primary sources, it doesn't include all of the possible print primary sources available to students and scholars around the world. Use WorldCat to find print primary sources within the Boston Library Consortium and around the world.