Pope Pius X
Pascendi Dominici Gregis §48
Pascendi Dominici Gregis: On the Doctrines of the Modernists
48 All these prescriptions and those of Our Predecessor are to be borne in mind whenever there is question of choosing directors and professors for seminaries and Catholic Universities. Anybody who in any way is found to be imbued with Modernism is to be excluded without compunction from these offices, and those who already occupy them are to be withdrawn. The same policy is to be adopted towards those who favour Modernism either by extolling the Modernists or excusing their culpable conduct, by criticising scholasticism, the Holy Father, or by refusing obedience to ecclesiastical authority in any of its depositaries; and towards those who show a love of novelty in history, archaeology, biblical exegesis, and finally towards those who neglect the sacred sciences or appear to prefer to them the profane. In all this question of studies, Venerable Brethren, you cannot be too watchful or too constant, but most of all in the choice of professors, for as a rule the students are modelled after the pattern of their masters. Strong in the consciousness of your duty, act always prudently but vigorously.
Source: Pascendi Dominici Gregis (Vatican.va)