Chapter 80:1
Some Activities Forbidden on Shabbos
(The principal "Melachos" which we are forbidden to perform on Shabbos are
well-known and therefore will not be mentioned here. The following listing
refers to laws which are not common knowledge, and yet frequently arise).
1.It is forbidden to use the light of an oil lamp for any activity which
requires some concentration (1). This was forbidden by the Sages lest one
inadvertently tilt the lamp in order to bring the oil closer to the wick,
thereby violating the [Biblical prohibition] called "Mav'ir" ("kindling" [a
fire]) (2). Two people, however, may read the same concept from a single
text, because if one of them attempts to tilt the lamp, his colleague will
remind him (3).
[Studying by the light of ] our present day candles, in which the wax or
tallow adhere to the wicks, is permitted (4). Nevertheless, one must make
some sort of mark in order to remember not to snip off the top of the wick
that has become charred. The Rambam (Maimonides) considers this to be the
violation of a Biblical prohibition (5). It is even forbidden to have a
Gentile cut off this portion of the wick.
FOOTNOTES:
(1) One is permitted to read portions of the prayers that are somewhat
familiar to you by the light of an oil lamp..
(2) "Mav'ir" is one of the 39 categories of activity forbidden on Shabbos.
(3) Most authorities permit this only for reading that is a Mitzvah, such
as Torah study or reciting Psalms.
(4) The basic principle is that any candle that never needs to be tilted in
order to improve its light, is not included in this prohibition (See Mishna
Berura 275:4).
(5) This prohibition is called "Tikkun Maneh" ("Creating a vessel"); in
other words, by cutting the one wick into two wicks, one has created a new
wick (See Rashi: Beitzah 32:b: D'H: "DeKoMesaken Maneh")
