To search by "Subject Headings" in the WRLC Catalog (NOT the Discovery Catalog), type the following. Then you will see the subject headings and can select a more specific subject heading, if desired, or select the broad subject heading for the results. You can also type something else as long as "plato" precedes the word. Examples:
Plato
plato
Apology
plato apology
Bibliography
plato bibliography
Congresses
plato congresses
Contributions in Metaphysics
plato contributions in metaphysics
Ethics
plato ethics
Theaetetus
plato theatetus
Timaeus
plato timaeus