Adam Smith, in his seminal work The Wealth of Nations, described wealth as "the annual produce of the land and labor of the society". This "produce" is, at its simplest, a good or service which satisfies human needs, and wants of utility. 

Adam Smith (1723 -90) defined economics as follows : 'Economics is the science of wealth'. He is the author of the famous book 'Wealth of Nations' (1776). He is known as the Father of Political Economy because he was the first person who put all the economic ideas in a systematic way. It is only after Adam Smith, we study economics as a systematic science.

Adam Smith, considered to be the founding father of modern Economics, defined Economics in his epoch making book "An Inquiry Into the Nature and Causes of the Wealth of Nations". The central point in Smith’s definition is wealth creation. Implicitly, Smith identified wealth with welfare. He assumed that the wealthier a nation becomes the happier are its citizens. Thus, it is important to find out how a nation can be wealthy. Economics is the subject that tells us how to make a nation wealthy. Adam Smith’s definition is a wealth-centred definition of Economics.  

The term 'wealth' has a special meaning in Economics. In the ordinary language, by 'wealth', we mean money, but in economics, wealth refers to those goods which satisfy human wants. But we should remember all goods which satisfy human wants are not wealth. For example, air and sunlight are essential for us. We cannot live without them. But they are not regarded as wealth because they are available in abundance and unlimited in supply. We consider only those goods which are relatively scarce and have money value as wealth. 

Adam Smith the founder of English Classical Economics defined as the study of the nature and causes of national wealth. Economics according to Smith was the study of wealth. How to increase its production and how to distribute it. He defined Economics as the Science of Wealth. Almost all classical economists defined the subject in a similar way.

Before Adam Smith there were other writers who expressed significant economy ideas. But economics as a separate branch of knowledge started with Adam Smith book. At its birth the name of economics was Political Economy. Towards the close of the 19th century there was a definite change in the use of word from political economy to “Economics”.