"There's No Getting Blood Out Of A Turnip"

Context: Years of service in the British navy, during which he progressed from midshipman to captain, provided background for many thrilling tales of adventure by the British novelist Frederick Marryat. He is perhaps best known for his Mr. Midshipman Easy (1836). He also wrote stories for children, and some poetry. Japhet in Search of a Father is one of Marryat's quartet of publications in 1836. It follows the pattern of Spain's picaresque novels, sometimes called "romances of roguery." Japhet and his faithful Timothy have qualities in common with Don Quixote and Sancho Panza, or with the galán hero and the gracioso servant of the Spanish Golden Age dramas of Cape and Sword. The rest of the figures in the book are stock characters: Mr. Phineas Cophagus and his catchwords, and the melodramatic Melchior and Netta. Only Aramathea Judd, the young girl who masquerades as her aunt, is something new. It is a pity that her creator discarded her so soon. The novel starts in true picaresque style in the first person with the arrival of the hero, Japhet, in a basket at a foundling home. Because he is quick to learn spelling and reading, and can write with a good round hand, he is prepared for a career in medicine, and apprenticed, along with Timothy, another boy, to an apothecary, Mr. Cophagus. The expression "getting blood out of a turnip" (or from a stone) as a description of an unrewarding task, is given a literal interpretation in Chapter 4.

. . . every evening I read surgical and medical books, put into my hands by Mr. Cophagus, who explained whenever I applied to him, and I soon obtained a very fair smattering of my profession. He also taught me how to bleed, by making me, in the first instance, puncture very scientifically all the larger veins of a cabbage-leaf, until well satisfied with the delicacy of my hand and the precision of my eye, he wound up his instructions by permitting me to breathe a vein in his own arm.
"Well," said Timothy, when he first saw me practicing, "I have often heard it said, 'there's no getting blood out of a turnip;' but it seems there is more chance with a cabbage. I tell you what, Japhet, you may try your hand upon me as much as you please for two-pence a go."