Don’t be fooled by the icon—Symeon the New Theologian is one fascinating saint!
Following the inspiration of the Spirit he charted his own course against the grain of the imperial court. When the official theologian of the day challenged his view of the Trinity, he answered quickly and counterattacked personally. When the court ordered him to quit venerating his spiritual father, he left his monastery in exile. (He even refused to return after the exile was lifted!)
Hunt’s Guide in the Cascade Companion series is an excellent introduction to Symeon. She clearly explains the politico-religious background of tenth century Byzantium, situating the saint firmly in his context.
The Eastern Orthodox tradition has many resources to offer the Western church. St. Symeon is a good place to start.
Hunt, Hannah. A Guide to St. Symeon the New Theologian. Cascade Companions. Eugene, OR: Cascade Books, 2015.