Answer to Question #64495 in Ecology for Sanjukta Ghosh

Question

Shelford’s Law of Tolerance states that the presence and success of an organism depend upon the completeness of a complex of conditions. Absence or failure of an organism can be controlled by qualitative or quantitative deficiency or excess with respect to any one of the several factors, which may approach the limits of tolerance for that organism. (Odum, 1971)

What I understand is the survival and distribution of a species is affected or rather controlled by the lower and upper limits of tolerance of a certain enviornmental (physio-chemical) factor e.g. Temperature.
What I don't understand is: what is meant by ''completeness of a complex of conditions'' and
''controlled by QUALITATIVE or QUANTITATIVE deficiency or excess''
When we put together these two things what does this law mean?