In his book The Jewish War, Josephus describes the Essenes, the Pharisees, and the Sadducees. There is only a short paragraph on the Pharisees and Sadducees:

14. But then as to the two other orders at first mentioned, the Pharisees are those who are esteemed most skillful in the exact explication of their laws, and introduce the first sect. These ascribe all to fate [or providence], and to God, and yet allow, that to act what is right, or the contrary, is principally in the power of men, although fate does co-operate in every action. They say that all souls are incorruptible, but that the souls of good men only are removed into other bodies, – but that the souls of bad men are subject to eternal punishment. But the Sadducees are those that compose the second order, and take away fate entirely, and suppose that God is not concerned in our doing or not doing what is evil; and they say, that to act what is good, or what is evil, is at men’s own choice, and that the one or the other belongs so to every one, that they may act as they please. They also take away the belief of the immortal duration of the soul, and the punishments and rewards in Hades. Moreover, the Pharisees are friendly to one another, and are for the exercise of concord, and regard for the public; but the behavior of the Sadducees one towards another is in some degree wild, and their conversation with those that are of their own party is as barbarous as if they were strangers to them. And this is what I had to say concerning the philosophic sects among the Jews.

The rest of the text (which actually comes before this paragraph) is devoted to the Essenes. The passage begins:

2. For there are three philosophical sects among the Jews. The followers of the first of which are the Pharisees; of the second, the Sadducees; and the third sect, which pretends to a severer discipline, are called Essens. These last are Jews by birth, and seem to have a greater affection for one another than the other sects have. These Essens reject pleasures as an evil, but esteem continence, and the conquest over our passions, to be virtue. They neglect wedlock, but choose out other persons children, while they are pliable, and fit for learning, and esteem them to be of their kindred, and form them according to their own manners. They do not absolutely deny the fitness of marriage, and the succession of mankind thereby continued; but they guard against the lascivious behavior of women, and are persuaded that none of them preserve their fidelity to one man.

3. These men are despisers of riches, and so very communicative as raises our admiration. Nor is there any one to be found among them who hath more than another; for it is a law among them, that those who come to them must let what they have be common to the whole order, – insomuch that among them all there is no appearance of poverty, or excess of riches, but every one’s possessions are intermingled with every other’s possessions; and so there is, as it were, one patrimony among all the brethren. They think that oil is a defilement; and if any one of them be anointed without his own approbation, it is wiped off his body; for they think to be sweaty is a good thing, as they do also to be clothed in white garments. They also have stewards appointed to take care of their common affairs, who every one of them have no separate business for any, but what is for the uses of them all.

4. They have no one certain city, but many of them dwell in every city; and if any of their sect come from other places, what they have lies open for them, just as if it were their own; and they go in to such as they never knew before, as if they had been ever so long acquainted with them. For which reason they carry nothing at all with them when they travel into remote parts, though still they take their weapons with them, for fear of thieves. Accordingly, there is, in every city where they live, one appointed particularly to take care of strangers, and to provide garments and other necessaries for them. But the habit and management of their bodies is such as children use who are in fear of their masters. Nor do they allow of the change of or of shoes till be first torn to pieces, or worn out by time. Nor do they either buy or sell any thing to one another; but every one of them gives what he hath to him that wanteth it, and receives from him again in lieu of it what may be convenient for himself; and although there be no requital made, they are fully allowed to take what they want of whomsoever they please.

5. And as for their piety towards God, it is very extraordinary; for before sun-rising they speak not a word about profane matters, but put up certain prayers which they have received from their forefathers, as if they made a supplication for its rising. After this every one of them are sent away by their curators, to exercise some of those arts wherein they are skilled, in which they labor with great diligence till the fifth hour. After which they assemble themselves together again into one place; and when they have clothed themselves in white veils, they then bathe their bodies in cold water. And after this purification is over, they every one meet together in an apartment of their own, into which it is not permitted to any of another sect to enter; while they go, after a pure manner, into the dining-room, as into a certain holy temple, and quietly set themselves down; upon which the baker lays them loaves in order; the cook also brings a single plate of one sort of food, and sets it before every one of them; but a priest says grace before meat; and it is unlawful for any one to taste of the food before grace be said. The same priest, when he hath dined, says grace again after meat; and when they begin, and when they end, they praise God, as he that bestows their food upon them; after which they lay aside their [white] garments, and betake themselves to their labors again till the evening; then they return home to supper, after the same manner; and if there be any strangers there, they sit down with them. Nor is there ever any clamor or disturbance to pollute their house, but they give every one leave to speak in their turn; which silence thus kept in their house appears to foreigners like some tremendous mystery; the cause of which is that perpetual sobriety they exercise, and the same settled measure of meat and drink that is allotted them, and that such as is abundantly sufficient for them.

6. And truly, as for other things, they do nothing but according to the injunctions of their curators; only these two things are done among them at everyone’s own free-will, which are to assist those that want it, and to show mercy; for they are permitted of their own accord to afford succor to such as deserve it, when they stand in need of it, and to bestow food on those that are in distress; but they cannot give any thing to their kindred without the curators. They dispense their anger after a just manner, and restrain their passion. They are eminent for fidelity, and are the ministers of peace; whatsoever they say also is firmer than an oath; but swearing is avoided by them, and they esteem it worse than perjury for they say that he who cannot be believed without [swearing by] God is already condemned. They also take great pains in studying the writings of the ancients, and choose out of them what is most for the advantage of their soul and body; and they inquire after such roots and medicinal stones as may cure their distempers.

As can be seen from this text, the Essenes are more like a religious order than like people who merely hold common opinions or keep to common traditions. The rest of Joseph’s discussion, which I will omit here, goes into this in more detail, explaining their customs of discipline and so on. Regarding their teaching, he says:

11. For their doctrine is this: That bodies are corruptible, and that the matter they are made of is not permanent; but that the souls are immortal, and continue for ever; and that they come out of the most subtile air, and are united to their bodies as to prisons, into which they are drawn by a certain natural enticement; but that when they are set free from the bonds of the flesh, they then, as released from a long bondage, rejoice and mount upward. And this is like the opinions of the Greeks, that good souls have their habitations beyond the ocean, in a region that is neither oppressed with storms of rain or snow, or with intense heat, but that this place is such as is refreshed by the gentle breathing of a west wind, that is perpetually blowing from the ocean; while they allot to bad souls a dark and tempestuous den, full of never-ceasing punishments. And indeed the Greeks seem to me to have followed the same notion, when they allot the islands of the blessed to their brave men, whom they call heroes and demi-gods; and to the souls of the wicked, the region of the ungodly, in Hades, where their fables relate that certain persons, such as Sisyphus, and Tantalus, and Ixion, and Tityus, are punished; which is built on this first supposition, that souls are immortal; and thence are those exhortations to virtue and dehortations from wickedness collected; whereby good men are bettered in the conduct of their life by the hope they have of reward after their death; and whereby the vehement inclinations of bad men to vice are restrained, by the fear and expectation they are in, that although they should lie concealed in this life, they should suffer immortal punishment after their death. These are the Divine doctrines of the Essens about the soul, which lay an unavoidable bait for such as have once had a taste of their philosophy.

The last clause, “which lay an unavoidable bait for such as have once had a taste of their philosophy,” suggests that Josephus finds the opinions and practices of the Essenes attractive, which may explain why he devotes so much of his text to them while giving only a short discussion of the Pharisees and Sadducees. In any case, as far the doctrine itself is concerned, it is more like the teaching of the Pharisees, except that the Essenes appear to believe in the immortality of the soul but perhaps not in the resurrection of the body, while the Pharisees believe in the resurrection.

There are noticeable similarities (although also noticeable differences) between the opinions and practices of the Essenes as described here and those of Christ, and indeed of the early Christian community as described by the book of Acts. Some of these similarities are the preference of continence to marriage, the despising of riches, the community of goods, carrying nothing while travelling, and the attitude towards oaths. There may be other similarities such as in regard to piety and charity, but these things are perhaps too general to indicate anything in particular.

Josephus is writing after the destruction of Jerusalem, perhaps around 75 AD, so even if his description is entirely accurate, things naturally might have been a bit different during the time of Christ’s ministry, which would have been 40 or 50 years earlier. And he also may be exaggerating some things, as for example when he says that the Sadducees believe that God does not care whether we do good or evil: this may simply be his way of describing their assertion that God does not reward or punish.