Medieval theologians distinguished rational illustration of the Trinity from rational proof

Evidence

Alan of Lille used explanations in his polemic against both Jews and Muslims; for example, unity begets itself, and between the begetting unity and the begotten unity there is a certain equality, so that there are three unities in one. Again, there is the vestige of the Trinity in the human soul which recollects, and loves, and understands, like candles burning with a single light. Alexander III’s development of the theme is classic: the ineffable Trinity ‘has so much more nicely the merit of faith that it is difficult to believe’. His approach was far removed from that which thought to ‘prove’. — Norman Daniel, Islam and the West, 975

Categorization

• DEFINE: Clarifies the distinction scholastic theologians drew between illustrating an ineffable mystery and proving it rationally — a genuine conceptual framework distinction.
• XREF: connects to: Rational proofs of the Trinity never convinced informed non-Christian disputants