That corporeal breath was not the substance of the Holy Ghost, but to shew, by meet symbol, that the Holy Ghost proceeded not only from the Father, but the Son. For who would be so mad as to say, that it was one Spirit which He gave by breathing, and another which He sent after His ascension?
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: iv. de Trin. c. xx