CONTRADICTION OF PROBABILITIES

I have now written two biographies.  The following is the truest remark on the genre I've yet to find:

"Too much intelligence is often as pernicious in biography as too little; the mind remains perplexed by contradiction of probabilities and finds difficulty in separating report from truth." Hester Lynch Piozzi, Anecdotes of Samuel Johnson (New Edition, 1826)

Slightly concerned that it might be thought I am claiming 'too much intelligence'. Of course y'all understand that 'intelligence' here means 'information'. (OED 6a. Knowledge concerning events communicated by or obtained from another).