From The Works of William Shakespeare. Vol. 19. Ed. Evangeline Maria O'Connor. J.D. Morris and Co.
Polonius is a man bred in courts, exercised in business, stored with observation, confident in his knowledge, proud of his eloquence, all declining into dotage. His mode of oratory is designed to ridicule the practice of those times, of prefaces that made no introduction,
and of method that embarrassed rather than explained. This part of his character is accidental, the rest natural. Such a man is positive and confident, because he knows
that his mind was once strong, and knows not that it has become weak. Such a man excels in general principles, but fails in particular application. He is knowing in retrospect, and ignorant in foresight. While he depends upon his memory, and can draw from his depositaries of knowledge, he utters weighty sentences, and gives useful counsel: but, as the mind in its enfeebled state cannot be kept long busy and intent, the old man is subject to the dereliction of his faculties; he loses the order of his ideas, and entangles himself in his own thoughts, till he recover the leading principle, and fall into his former train. The idea of dotage encroaching upon wisdom will solve all the phenomena of the character of Polonius.
Johnson: General Observations on Shakespeare's Plays.
Habits of intrigue having extinguished in Polonius the powers of honest insight and special discernment, he therefore perceives not the unfitness of his old methods to the new exigency; while at the same time his faith in the craft, hitherto found so successful, stuffs him with
overweening assurance. Hence, also, that singular but most characteristic specimen of grannyism, namely, his pedantic and impertinent dallying with artful turns of thought and speech amidst serious business; where he appears not unlike a certain person who "could speak
no sense in several languages." Superannuated politicians, indeed, like him, seldom have any strength but as they fall back upon the resources of memory: out of these, the ashes, so to speak, of extinct faculties, they may seem wise after the fountains of wisdom are dried
up within them; as a man who has lost his sight may seem to distinguish colours, so long as he refrains from speaking of the colours that are before him.
Hudson: The Works of Shakespeare.