For Frege, we get the sense of a sentence because of the functions of its constituent parts. In order to know the meaning of a sentence we need to know the meaning of its constituent parts and what they refer to. So every meaningful sentence must have a reference. Further, he states that expression without reference is not necessarily meaningless. It is so because there are cases where the propositions have meanings but do not refer to any object. For example, "Honesty is desirable". This proposition has sense, as a result, we understand what it expresses. But the constituent parts of this sentence do not refer to any object. There are no such objects called honest and desire found in this phenomenal world. So, this proposition has sense but not reference.

A question is raised here, how do we acquire the sense of a proposition? The answer is given by Frege. According to him, a proposition is constituted with some words and each word has a specific meaning. Words have meaning but they are not meaning themselves. When we classify words as meaningful and meaningless, we just describe the situations where they are acting as successful symbols and where they are not. By elaborating more he states that if I know the meaning of a word, then I have also known in what combinations it can occur and in what combinations it cannot. For example, if I know the meaning of the word 'rain' then I can understand the following propositions:

It is raining.
He was fond of preserving the rainwater.

In this way we can acquire the sense of the propositions.

But, there are some words, such as celestial city, craving, anxiety, honesty, punctuality, do not refer to anything. So how is it possible for us to get the meanings of those sentences (propositions) which are made of such words? Frege answers that the meaning of an expression not only corresponds to object, but also to concept.³ For example, "Mr. X died in 1942". In this sentence, 'Mr. X' does not have a referent. So in order to understand the meaning of this sentence we refer to the concept that 'Mr. X' was a person who died in 1942 and is no more in this world. Here, we refer to the concept but not to the object. Thus we get the sense of this sentence. Further, if we examine some of the stanzas of a poem, we find that the poet due to his or her imaginations or speculations writes those. So the stanzas of the poem do not correspond to any object but correspond to the concept. Hence, we are able to get the sense of the stanzas of the poem, which may be represented in the form of assertive sentences. In this David Bell⁴ (1996) points out that if we have a stock of concepts and if we bring them together with their logical necessity and applicability, we can produce a new concept. Hence, we can refer to that concept. For example, by combining the concepts 'fox' and 'female' we can have a new concept called 'vixen', which can serve as a referent.

³	Parkinson,G.H.R. (1988). An Encyclopedia of Philosophy, 11 New FetterLane, London: Routledge Publication, p.26.
⁴	Bell,D. (1996). The Formation of Concepts and the Structure of Thoughts, Philosophy and Phenomenological Research, 56, p. 589.