With regards to the lighting of Shabbat candles, the Sages are concerned lest the proximity to a burning candle might lead to prohibited actions of kindling or extinguishing the flame. In this context the set-up of the oil lamp is examined. In the case of an oil lamp with a wick one can claim that the burning of each and every drop of oil began before Shabbat and is merely continuing on Shabbat. However, when oil is added from an eggshell or from an additional vessel (as seen above), the additional oil will only reach the wick on Shabbat itself. It will only begin burning then, which is tantamount to having been lit on Shabbat.