Who when a faulty statement was written is reputed to have said"I didn't check my reference, because i didn't know I didn't know" and who said "Ignorance,Madam pure ignorance"
The second is Dr Johnson, being challenged by a lady who wanted to know why his dictionary had 'pastern' as 'the knee of a horse' ! He corrected that in later editions (it's the part of a horse's foot between the fetlock and the hoof. If anything, it's the 'ankle' of a horse )