You are given a candle, a box of matches, a few thumbtacks, and a very short piece of string with the instruction to mount the candle on a wall. It never occurs to you that you could empty the matchbox and tack it to the wall as a platform for the candle because of .

Functional fixedness      

Explanation:

You are given a candle, a box of matches, a few thumbtacks, and a very short piece of string with the instruction to mount the candle on a wall. It never occurs to you that you could empty the matchbox and tack it to the wall as a platform for the candle because of functional fixedness. Functional  fixedness is a cognitive bias that makes individuals not to see the alternative ways to use an item apart for the traditional purpose for which it was made.

depends on what they need

for many centuries there were important factors which the economies of the muslim empires developed increasingly. they applied economic procedures in production, investment, finance, taxation and property. they used to tax certain goods (for example: harvest), they charged interest on money lent, they signed contracts with merchants; they relied on a common currency, and they used checks as well as promissory notes. with the money collected by means of taxation, the government provided the needy with an income. in addition, trading networks covered huge distances, so far regions started to have contact and exchange goods. this trade network covered areas of asia, africa and europe.