‘The fault, dear Brutus, is not in our stars, / But in ourselves’; ‘Why, man, he doth bestride the narrow world / Like a Colossus’. In just over half a dozen lines, Cassius gives us two of the most famous lines from Shakespeare’s Julius Caesar. His ‘bestride the narrow world like a Colossus’ speech – or, if you prefer, his ‘The fault, dear Brutus, is not in our stars’ speech – is a crucial one in the play.
Let’s take a closer look at why it’s such an important passage in Shakespeare’s play. Perhaps the best way to provide an analysis of Cassius’ words is by going through the speech, summarising its meaning as we go.
Why, man, he doth bestride the narrow world
Like a Colossus, and we petty men
Walk under his huge legs and peep about
To find ourselves dishonourable graves.
Cassius begins his speech by responding to Brutus, who has just himself responded to the sound of applause that can be heard, honouring Julius Caesar. Brutus said that the ‘applauses are / For some new honours that are heaped on Caesar.’
The image of Julius Caesar, the mighty general, straddling the whole world like a ‘Colossus’ summons the Colossus of Rhodes, a giant bronze statue of Apollo that was one of the Seven Wonders of the Ancient World. There was a common belief that this statue straddled the harbour in Rhodes, although this is almost certainly wrong. Nevertheless, it’s a powerful mental image: Julius Caesar standing mighty and tall across the world, which seems ‘narrow’ in comparison with the might of this great ruler.
By contrast, Brutus and Cassius are small or insignificant men (‘petty men’) who walk under the huge parted legs of Julius Caesar. And their whole lives are spent not conquering the world (as Caesar has done) but in merely finding some quiet spot to die, insignificant and forgotten.
Men at some time are masters of their fates:
The fault, dear Brutus, is not in our stars,
But in ourselves, that we are underlings.
Here we come to one of the most famous lines in Julius Caesar, and perhaps in all of Shakespeare, and an expression which the contemporary US novelist John Green turned on its head for the title of his book The Fault in Our Stars.
Note that Cassius says: ‘The fault, dear Brutus, is not in our stars’, rather than ‘The fault, dear Brutus, lies not in our stars’ (which is how it is often misquoted). ‘Men at some time are masters of their fates’ means that human beings do 
actually have some control over their destiny, and it lets us off the hook, Cassius argues, to believe that we have no free will or agency to carve out our own fortune.
Indeed, Julius Caesar is such a man; though it is worth noting that the whole play is about the tension between individual action and preordained destiny. The soothsayer will famously warn Caesar to ‘beware the ides of March’, which turns out to be the day on which Caesar is assassinated. Could Caesar have averted his grisly fate if he had taken the soothsayer’s warning more seriously? What role did fate play in making his death inevitable, given that the soothsayer clearly had a premonition that that day was fated to be unlucky for him?
But clearly Cassius is of the firm belief that he and Brutus are mere subordinates or ‘underlings’ at the feet of their great ruler because of their own failure to change their circumstances, rather than because the ‘stars’ or fates have decided that they will be underlings: ‘The fault … is not in our stars, / But in ourselves’. We are to blame.
Brutus and Caesar: what should be in that ‘Caesar’?
Why should that name be sounded more than yours?
Write them together, yours is as fair a name;
Sound them, it doth become the mouth as well;
Weigh them, it is as heavy; conjure with ’em,
Brutus will start a spirit as soon as Caesar.
We might draw a parallel with Juliet’s famous (and similarly rhetorical) question in Romeo and Juliet: ‘What’s in a name? That which we call a rose / By any other word would smell as sweet.’ There is nothing in either ‘Brutus’ or ‘Caesar’ which possesses magical advantage over the other name, to foretell the fates of the two individuals who bear those names.
So, if Brutus started to ‘conjure’ with his name (the expression ‘a name to conjure with’ has come to mean a well-respected and powerful name belonging to someone of influence and reputation, though as the word ‘conjure’ suggests, it originally denoted a belief that the name could be used as an incantation to summon spirits or raise the dead: hence Cassius’ phrase ‘start a spirit’, where ‘start’ means both ‘begin’ and ‘startle’ or ‘disturb’).
As David Daniell observes in his brilliant notes to the play in the Julius Caesar-Arden Shakespeare edition, citing Kittredge, the name ‘Caesar’ was an insignificant name in history until Julius Caesar made it one of the most famous. By contrast, ‘Brutus’ was, before Julius Caesar came along, ‘the greatest name in Roman annals’ (Kittredge).
Now, in the names of all the gods at once,
Upon what meat doth this our Caesar feed,
That he is grown so great? Age, thou art shamed!
Rome, thou hast lost the breed of noble bloods!
However, spirits could only be raised by using the name of a god, so ‘Caesar’ must have been up to something unusual or even suspicious, Cassius insinuates, to have raised himself – a man, not a god – so high. (‘Meat’ in this context, as throughout the medieval and early modern period, was just synonymous with ‘food’; it hadn’t yet acquired its narrower and more specific meaning.)
Cassius laments that the age in which they live has become so debased (‘Age, thou art shamed!’), that a general like Caesar could have raised himself to such a status. Rome, a once-great city and empire, appears to have lost its noble lineage, that such an ordinary man as Caesar (who wasn’t born into a family of good name) could have become so powerful.
When went there by an age, since the great flood,
But it was famed with more than with one man?
When could they say till now, that talk’d of Rome,
That her wide walks encompass’d but one man?
Cassius employs rhetorical questions to drive his point further home: when has there ever been such a time in the history of the world, ever since the biblical flood (the story of which we have analysed here), when one man alone dominated the political scene? (Note: some editors amend ‘wide walks’ to ‘wide walls’, but Daniell advises against that, on the basis that we can find references to ‘wide walks’ elsewhere in Shakespeare, but never wide walls.)
Now is it Rome indeed and room enough,
When there is in it but one only man.
There is a pun here on ‘Rome’ and ‘room’, which could be homophones in Shakespeare’s time: Rome was rhymed with both dome and doom. Cassius’ point is that, as far as Rome and Caesar are concerned, there is room for only one man: Julius Caesar himself. The implication is that Caesar will allow for no one else to take his mantle or power away from him.
O, you and I have heard our fathers say,
There was a Brutus once that would have brook’d
The eternal devil to keep his state in Rome
As easily as a king.
Cassius concludes his speech by reminding Brutus, his companion, that his namesake founded the city of Rome centuries before. (Legend states that Lucius Junius Brutus founded the Roman Republic in around 509 BC.) This earlier Brutus would have let a devil rule in Rome before he let a king rule. After all, Rome was founded as a republic, i.e., a state that isn’t ruled by a king; and yet Julius Caesar has set himself up as an absolute ruler much like a king in all but name.