Read not books alone, but men, and amongst them chiefly thyself. If thou find anything questionable there, use the commentary of a severe friend rather than the gloss of a sweet lipped flatterer; there is more profit in a distasteful truth than in deceitful sweetness. - Francis Quarles
A flatterer is a friend who is your inferior, or pretends to be so. - Aristotle
Hope is nothing but a deceitful flatterer accepted by reason only because it is often in need of palliatives. - Giacomo Casanova