Shabbat is the source of blessing and abundance for the entire week, both spiritually and materially. Candle lighting, Kiddush (the blessing recited over wine to sanctify the Shabbat day), and the loaves of halla symbolize basic human needs, on which Shabbat has an effect.

The days of the week are like the branches of the candelabrum in the Temple:

The body of the candelabrum, [on] which is the middle lamp, alludes to Shabbat. There are three lamps to the right and three to the left. Three allude to Wednesday, Thursday, and Friday, when we prepare for Shabbat; and three allude to Sunday, Monday, and Tuesday, as on those days some of the enhanced soul, spirit, and life force of Shabbat still remain…

Candle lighting, Kiddush, and halla hint to all human needs, which are blessed on Shabbat:

It is known that all sustenance that is allotted to us is a result of the sanctity of Shabbat. Therefore, at the beginning of Shabbat, when night falls, we sanctify Shabbat with grain, wine, and oil. There must be a table with bread on it, i.e., grain, and one must make Kiddush on the wine, and light the candles using oil. It is known that the general blessing of sustenance of humankind includes “your grain, your wine, and your oil” (Deuteronomy 7:13 inter alia).… Divine abundance of food comes to Israel as a result of the holiness of Shabbat, as the Sages said: “The blessing of the Lord, it will enrich” (Proverbs 10:22); this is Shabbat (Bereshit Rabba 11:1). (Rabbi Yosef Ĥayyim, Ben Ish Ĥai, Year 2, Pekudei)

Further reading: For more on the smelling of spices at Havdala, an act that relates to the additional soul of Shabbat, see A Concise Guide to Halakha, p. 400.

Rabbi Nata of Avritch, one of the students of the Ba’al Shem Tov, used to refrain from sleeping on Shabbat. He would say: The Torah commanded: “The children of Israel shall keep [veshamru, literally guard] Shabbat” (Exodus 31:16); and would a guard sleep while standing at his post?

When word spread of Napoleon, it was said that the emperor slept very little, saying: “It would be a pity to waste a moment of my reign by sleeping.” This statement reached Rabbi Nata, who saw it as justification of his custom: For on Shabbat, all of Israel are kings; and would a person who has been appointed king for one day waste the moments of his reign by sleeping?

Shabbat is greater than the World to Come, as Shabbat is the spring from which the World to Come was drawn. (Rabbi Barukh of Medzhybizh)

On Shabbat, heavenly joy is revealed in actuality. (Rabbi Shneur Zalman of Liadi)

Shabbat is like the World to Come, because on this day one allays every thirst in his soul and spends an entire day satisfying its desires and longings to connect to its blessed Creator, without any external hindrances. (Rabbi Menaĥem Ekstein, Tena’ei HaNefesh LeHasagat HaĤasidut)

Further reading: For more on the World to Come, see p. 165.