I wrote my final paper on the often ignored Letters to Serapion on the Holy Spirit written by Athanasius of Alexandria which he wrote to combat the heresy of the “Tropici” who denied the divinity of the Holy Spirit. Although it is a useful source for early Christian pneumatology it has often been ignored. This is likely because it is overshadowed by a very similar work written by Basil the Great (On the Holy Spirit). The abstract for the paper is this:
The Letters to Serapion on the Holy Spirit were written by Athanasius to address the heresy of the Tropici. These letters have been neglected by many scholars of early Christian theology. In my paper I will seek to introduce this work to a first time reader. This will include discussions on authorship, the context, the audience, and the opponents against whom this was written. Since these letters were written to combat the teaching that the Holy Spirit is a created being it is a primary source for early Patristic Pneumatology. It describes the Spirit as being closely related to the work of the Son who is the image of the Father. In other words, this is an apologetic for preserving the Trinity as Trinity.
You can download the PDF form here: LePort. An Introduction to The Letters to Serapion on the Holy Spirit by Athanasius of Alexandria