Neymar scored either side of another Luis Suarez volley, before Lionel Messi netted late on as the Catalan outfit stretched their lead at the top of the La Liga table to seven points and nine from Real Madrid.
That lead was since cut to four points, however, with Atletico Madrid responding with a 1-0 win over Espanyol.
As for Sociedad, it was an unhappy return to Camp Nou for Eusebio Sacristan, whose team remain 14th in the division and have now lost on their last 18 league visits to Barcelona.
Here, Sports Mole has dissected the 90 minutes of action in Barcelona.
On target: 6
On target: 2
Was the result fair?
It is difficult to imagine that Sociedad boss Eusebio will be too disappointed with his team's performance at Barcelona, which is somewhat of a strange statement due to the fact that the Basque side were beaten 4-0. Eusebio, on his return to Barcelona, sent out a team full of invention and the fact that they had 10 shots - just one less than Barcelona - is an indication of their approach. It did not come off in terms of the scoreline, but that was down to Barcelona's own brilliance rather than bad play on Sociedad's part. They are not the first team to have struggled against Luis Enrique's outfit this season and will not be the last.
One look at the statistics would suggest that it was a tight game, but that was not the case. Barcelona took a little bit of time to get going, but after opening the scoring in the 22nd minute, there was only ever likely to be one result. Suarez made it 2-0 late in the first period and that was a real blow to Sociedad's chances. Neymar's second early in the second period made the three points certain, before Messi added gloss to the scoreline in stoppage time. There is no question that the Catalan side deserved to record all the points and the fact that Sociedad played quite well makes the result even more impressive.
Barcelona boss Enrique resisted the temptation to rest either Messi, Neymar or Suarez, but there was a change at left-back as Jeremy Mathieu came in for Jordi Alba. Sergi Roberto's injury also meant a return to the XI for Andres Iniesta, who was named on the bench for the Champions League clash with Roma. It was Iniesta that came closest to opening the scoring at Camp Nou, but after meeting a cross from Suarez, the Spaniard rattled the post with his header. The goal was coming after a strong start, however, and it was Neymar that converted a low Alves cross to send the hosts ahead.
Alves's willingness to venture forward was a key feature of Barcelona's work in the first period and it was through that avenue that the second goal came, with the right-back setting up Suarez, who rattled another wonderful volley into the back of the net. It took a little bit of time for Enrique's team to get going in the second period, but they had their third in the 53rd minute when Mathieu sent a low cross into the box and Neymar just could not pass up the chance. At that point, Sociedad were staring down the barrel of a bit of a hiding as Neymar, Messi and Suarez continued to turn the screw up top.
It ultimately took until second-half stoppage time for Barcelona to score their fourth, however, with Messi, who had tried and failed with a number of chances in the second period, converting at the far post after more brilliant work from Neymar. To watch, it all seemed very simple for Barcelona, but that is due to the fact that it comes so easily to players of this ilk. Sociedad did not really threaten the home side's back four for long spells, but that was also down to Barcelona's domination of the game. In this form, it is difficult to see how any team can stop them in either La Liga or the Champions League. It used to be all about Messi and his goals, but Suarez and Neymar are also both in the form of their careers.
The team news from the visitors was very interesting, with Carlos Vela included in Eusebio's XI despite strong speculation linking the Mexican with a move to the MLS. Indeed, Vela was left out of the squad last weekend, but came into what was an attacking team at Camp Nou. The onus would be on Imanol Agirretxe to score the goals, but the feeling on social media before the match was that the supporters were happy with a side that also included the skipper Xabi Prieto. Indeed, Sociedad made it difficult for Barcelona in the early exchanges with their willingness to commit players forward.
Roma's suffered with a high line in the Champions League, however, and Sociedad's own willingness to use that tactic was also present in the first period. Excellent goalkeeping from Geronimo Rulli prevented Barcelona from having a couple of clear chances early on, but when the hosts upped the tempo, Sociedad found it difficult to cope. Alves had all sorts of space when he set up both goals in the first period, with Inigo Martinez losing his man on both occasions. After playing quite well in the opening 45 minutes, Sociedad entered the interval trailing 2-0 and it was always going to be difficult to respond.
Eusebio made changes as the second period developed, but by that point, his team were already 3-0 behind after Neymar had converted in the 53rd minute. Again the goal came from a wide area, which will have disappointed the manager. Bruma was one of those that added pace and invention to Sociedad in the latter stages and they threatened to end the game on top, but it was Messi that had the last laugh after another cross from the left. How Sociedad fare this season is not going to depend on their results at places such as Camp Nou and they can take some positives despite the defeat.
Sports Mole's man of the match
Neymar: It is difficult to put into words just how well Neymar is playing at the moment and the Brazilian continued his excellent form with another fine performance against Sociedad. It was the 23-year-old that opened the scoring in the 22nd minute and he remained a constant threat to the visiting team until the final stages, when he set up Messi for the Argentine's first of the afternoon. Sociedad just could not live with his movement in the final third. The attacker has netted 16 times in 17 games this season.
It is difficult to pick out one exact moment in terms of a gaffe, but Sociedad's defending in wide areas was very disappointing. All four Barcelona goals came either directly or indirectly from crosses and the visitors will feel that they could have done more to close the space in wide positions. Crowding the area outside the penalty box is a well-known tactic against Barcelona, but Sociedad did not undertake their duties when the pitch became stretched. It is not as if Barcelona need help to find the back of the net.
Referee Ignacio Iglesias issued five yellow cards at Camp Nou, all to the visitors. Most of the bookings were routine decisions, however, and there was not really a major call for the official had to make. Iglesias was not seen for long spells of the contest, which is usually a good sign.
Barcelona: The Catalan outfit will play the second leg of their Copa del Rey last-32 clash at home to Villanovense on Wednesday. Next weekend, they will continue their league campaign with a trip to Valencia.
Sociedad: Sociedad's Copa del Rey campaign for the 2015-16 season will begin away to Las Palmas on Thursday. Their next league match is at home to surprise package Eibar next Sunday.