One of the sources on which Shakespeare drew for the figure of Shylock, and especially for his speeches in the trial scene, is The Orator of Alexander Silvayn. The 95th Declamation of this work bears the title: "Of a Jew who would for his debt have a pound of the flesh of a Christian." Since an English translation of Silvayn's book by Anthony Munday appeared in 1596, and The Merchant of Venice is mentioned by Meres in 1598 as one of Shakespeare's works, there can scarcely be any doubt that the play was produced between these dates.
In The Orator both the Merchant and the Jew make speeches, and the invective against the Jew is interesting in so far as it gives a lively impression of the current accusations of the period against the Israelitish race:—
"But it is no marvaile if this race be so obstinat and cruell against us, for they doe it of set purpose to offend our God whom they have crucified: and wherefore? Because he was holie, as he is yet so reputed of this worthy Turkish nation: but what shall I say? Their own bible is full of their rebellion against God, against their Priests, Judges, and leaders. What did not the verie Patriarks themselves, from, whom they have their beginning? They sold their brother...." &c.
Shakespeare's chief authority, however, for the whole play was obviously the story of Gianetto, which occurs in the collection entitled Il Pecorone, by Ser Giovanni Fiorentino, published in Milan in 1558.
A young merchant named Gianetto comes with a richly laden ship to a harbour near the castle of Belmonte, where dwells a lovely young widow. She has many suitors, and is, indeed, prepared to surrender her hand and her fortune, but only on one condition, which no one has hitherto succeeded in fulfilling, and which is stated with mediæval simplicity and directness. She challenges the aspirant, at nightfall, to share her bed and make her his own; but at the same time she gives him a sleeping-draught which plunges him in profound unconsciousness from the moment his head touches the pillow, so that at daybreak he has forfeited his ship and its cargo to the fair lady, and is sent on his way, despoiled and put to shame.
This misfortune happens to Gianetto; but he is so deeply in love that he returns to Venice and induces his kind foster-father, Ansaldo, to fit out another ship for him. But his second visit to Belmonte ends no less disastrously, and in order to enable him to make a third attempt his foster-father is forced to borrow 10,000 ducats from a Jew, upon the conditions which we know. By following the advice of a kindly-disposed waiting-woman, the young man this time escapes the danger, becomes a happy bridegroom, and in his rapture forgets Ansaldo's obligation to the Jew. He is not reminded of it until the very day when it falls due, and then his wife insists that he shall instantly start for Venice, taking with him a sum of 100,000 ducats. She herself presently follows, dressed as an advocate, and appears in Venice as a young lawyer of great reputation, from Bologna. The Jew rejects every proposition for the deliverance of Ansaldo, even the 100,000 ducats. Then the trial-scene proceeds, just as in Shakespeare; Gianetto's young wife delivers judgment, like Portia; the Jew receives not a stiver, and dares not shed a drop of Ansaldo's blood. When Gianetto, in his gratitude, offers the young advocate the whole 100,000 ducats, she, as in the play, demands nothing but the ring which Gianetto has received from his wife; and the tale ends with the same gay unravelling of the sportive complication, which gives Shakespeare the matter for his fifth act.
Being unable to make use of the condition imposed by the fair lady of Belmonte in Il Pecorone, Shakespeare cast about for another, and found it in the Gesta Romanorum, in the tale of the three caskets, of gold, silver, and lead. Here it is a young girl who makes the choice in order to win the Emperor's son. The inscription on the golden casket promises that whoever chooses that shall find what he deserves. The girl rejects this out of humility, and rightly, since it proves to contain dead men's bones. The inscription on the silver casket promises to whoever chooses it what his nature craves. The girl rejects that also; for, as she says naïvely, "My nature craves for fleshly delights." Finally, the leaden casket promises that whoever chooses it shall find what God has decreed for him; and it proves to be full of jewels.
In Shakespeare, Portia, in accordance with her father's will, makes her suitors choose between the three caskets (here furnished with other legends), of which the humblest contains her portrait.
It is not probable that Shakespeare made any use of an older play, now lost, of which Stephen Gosson, in his School of Abuse (1579), says that it represented "the greedinesse of worldly chusers, and the bloody mindes of usurers."
The great value of The Merchant of Venice lies in the depth and seriousness which Shakespeare has imparted to the vague outlines of character presented by the old stories, and in the ravishing moonlight melodies which bring the drama to a close.