NERISSA: You need not fear, lady, the having any of these lords; they have acquainted me with their determinations, which is indeed to return to their home, and to trouble you with no more suit, unless you may be won by some other sort than your father's imposition, depending on the caskets.There are six suitors and, according to Nerissa, they are all leaving, so why does the servingman say there are four strangers about to leave and a fifth about to arrive?
Why did Shakespeare bother mentioning a specific number of strangers, anyway? The passage is written in prose, so he could have easily avoided including the word "four" or any number, whatsoever. He was no fool, he knew exactly what he was writing. Every word is there for a reason. He wrote "four" because that is what he wanted spoken. Although it is in prose he may have chosen words that, taken together, sound "good" in a poetic sense.
--------------------------------------------------------------------------stranger: its derivation comes from the French. After the Norman Conquest, 1066, there were lots of Frenchmen in England. These foreigners introduced a vast number of French words into the English language including their word for foreigner. The Old French word for "foreigner" was "estrangier" but this changed. It became, in Middle English (to 1470), "estranger" and then "stranger" in Early Modern English (to 1650).
So, of the six suitors, there are only four strangers who, by definition, are foreigners. The other two are not strangers, they are both Italian-speaking inhabitants of independent states within Italy. One is from Naples (the Neapolitan). The other is from Rome (the Palatine is one of the seven hills of Rome). Count Palatine, is of the Holy Roman Empire, which is not necessarily Italian but because of its link to the Church of Rome, this suitor probably speaks both Latin and Italian. Though the states from where they came may, at that time, have been autonomous they were still part of greater Italy and therefore unlikely to be classed as foreigners. Portia indicates that she speaks both Latin and Italian, so she would hardly regard these two suitors as foreigners.
As indicated, the other four suitors are all foreigners. There are, therefore, only four strangers who can take their leave, and they are about to do so, as soon as Portia turns up. We may speculate as to why the foreigners are together. Possibly it is to board a ship to take them from Belmont to Venice (20 miles away) and then home:
... to the common ferry
Which trades to Venice.
The two Italian suitors would not go by ship but travel overland, the Neapolitan on his horse, presumably.
From the text of the play (see extracts below) we note that the characters though living in Venice, freely mention Italy and Rome in such a way as to indicate that Venice, Rome, Italy are all one as a country and as a people. We note that the disguised Portia comes into court as Balthasar, a Doctor of Laws, of Rome.
We also note that Shylock, though living in Venice, is not considered to be Italian or even Venetian but is named as a stranger and his daughter, Jessica, is also called a stranger. Shylock suffers laws specifically for application to foreigners only.
Shylock is also called an alien, the one and only time a person is described so in all of Shakespeare, though we note that in "As You Like It" Celia gives herself the name "Aliena" when she forsakes her father's court to go with her banished friend Rosalind.
Thus alien = stranger but as neither the Neapolitan nor the Count Palatine are aliens, we have further indication that there were only four strangers.
(1) When the first of the suitors arrived at the departure point, the servingman was asked to go to Portia and request her to join them so that they might take their leave. The servingman may not have known how many suitors were paying court to Portia, but whether there were six or sixty, it doesn't matter to him for he is hardly likely to wait until they all arrive at the departure point before going on his errand. He would go the moment he was asked to do so. As he left, he noted that four of the strangers had already arrived at the departure point.
(2) Although there are six suitors, all six don't have to leave at the same time. Even if they are leaving today would they all be together or wish to be together? Hardly! The Englishman can't talk the language and may be unaware that the others are about to leave. Someone might suggest that because the Scotsman can talk English he ought to go and tell him. The Scotsman would likely refuse to do so, because he had his ears boxed by the Englishman and he wouldn't risk a repeat attack. The German, who is always drunk, may prefer to stay on and drink free grog until he gets kicked out!