UPDATE: The prefaces and appendices are now searchable (and appear in the list on the Individual Elements page to which the search function links). At some point in the near future I will fine-tune this to display just the particular sentences in which a term occurs.
This is experimental. It searches all three languages and displays each proposition in which a term occurs, even if it occurs more than once. Each entry can be expanded to show the first line of its parent element.
Use underscores to search for phrases or as a wildcard. E.g., 'deus_sive_substantia' (without quotation marks), or 'deu_'. Without underscores, searches will return both the exact phrase and instances of one or more of the terms.