‘The theologian of the Holy Spirit’ is how B.B. Warfield described John Calvin, whose birth in 1509 we celebrate this year. With Calvin, pneumatology (the doctrine of the Holy Spirit) came of age, being founded squarely on the Bible.
Every age needs a good theology of the Holy Spirit, perhaps especially ours where, on one side, it is often limited to miraculous power and gifts and, on the other, to the illumination (understanding) of biblical truth and not a lot more. The activity of the Holy Spirit is far richer and broader than that and a healthy theology (and Christian life) will recognise it.
