“Acquire the Holy Spirit, and a thousand around you will be saved." —St. Seraphim of Sarov
Another translation, from the Orthodox Church, has it, "Acquire a peaceful spirit, and around you thousands will be saved."
Both Orthodox and Roman Catholic historians agree on this quote:
"It is necessary that the Holy Spirit enter our heart. Everything good that we do, that we do for Christ, is given to us by the Holy Spirit, but prayer most of all, which is always available to us."
Saint Seraphim was a great ascetic and wonder worker, but even more important for future generations was his teaching on the essence of the Christian life. Firmly based in the patristic tradition, this teaching emphasizes seeking communion with God as the true purpose of life for every Christian. St. Seraphim demonstrated that everything else did nothing but offer the means for "acquiring the Holy Spirit."
He stressed that in the parable of the wise and foolish virgins, the oil, which the ten foolish virgins ran out of, is to be interpreted as the grace of the Holy Spirit. While engaging in external works of piety, these foolish virgins assumed that this was the essence of Christian life. They did not stop to think whether these acts were really pleasing unto God, whether they helped them gain the grace of the Spirit of God and made them worthy of this grace.
In his teaching, St. Seraphim contrasted moralism with genuine spirituality. The Spirit is granted but it can also be taken away. To acquire it one must engage in spiritual struggle.
He lived from Aug 1, 1794 to Jan 14, 1833 in the Russian Empire. His feastday is January 15 on Orthodox calendar and January 2 on the Roman Catholic calendar.
(Some information from Russian Orthodox Readings, 1990/2, Moscow Patriarchate publication http://www.roca.org/OA/105/105b.htm)