Frank J. Wilstach, comp. A Dictionary of Similes. 1916.

Hard (Adverb)

Hard as being good.
—Anonymous

As hard as to shave an egg.
—Anonymous

As hard to answer as why cats love fish.
—Anonymous

Hard to climb as Parnassus.
—Anonymous

As hard to hold as an eel by the tail.
—Anonymous

As hard as for an empty sack to stand upright.
—Benjamin Franklin

Hard as death.
—Nathaniel Hawthorne

Hard to enter my belief as Dives into heaven.
—Thomas Heywood