It is possible that a greater refinement of manners may give birth to finer distinctions of satire and a nicer tact for the ridiculous; but our insular situation and character are, I should say, most likely to foster, as they have in fact fostered, the great quantity of natural and striking humour, in spite of our plodding tenaciousness, and want both of gaiety and quickness of perception.
— William Hazlitt (1778–1830), via bartleby.com
I assume want in the last clause is a verb, not a noun, but I am not sure what is its subject. Can anyone share more insights here?