Michael Faraday's The Chemical History of a Candle

Guide to Lecture One
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So, the heat directly melts the wax within the candle and
indirectly cools the wax on the outside.
A candle must be able to form this symmetrical cup to
be useful; as Faraday notes, the “great beauty in a candle”
comes from its utility and that “good looking candles are
bad burning ones.” For example, non-cylindrical candles,
perhaps one shaped like a face or a figurine, burn to form a
non-symmetric cup, which, because of an uneven thickness
will “gutter.” Molten wax will leak through these gutters
down the sides of the candle.
We can generalize this insight to all scientific endeavors:
“the greatest mistakes and faults with regard to candles, as in
many other things” teach us something we otherwise would
not have known. Thus, a negative result is as important as
a positive result as long as we take the opportunity to learn
something from it. That is,
we come here to be scientists 1 … [and] whenever a result
happens, especially if it be new, you should say, “What is
the cause? Why does it occur” and you will in the course
of time find out the reason.
This nicely sums up the nature of science and is a theme
that permeates all of these lectures.
By examining the action of the heat of the flame, we
can learn about the difference between physical and chemical
changes. The heat is responsible for “disturbing its
[the wax’s] proper form if it comes only too near,” which