### Core Meaning & Semantic Range
The Greek word **nephrós**, represented by `{{G3510}}`, refers to a kidney, but is used figuratively in scripture to mean the **inmost mind**. This term, translated as **reins**, appears only **1 time** in **1 unique verse**, yet it carries significant weight in its singular context.
### Biblical Occurrences & Contextual Analysis
The sole appearance of `{{G3510}}` is in [[Revelation 2:23]], where Christ declares, "I am he which searcheth the **reins** and hearts." In this passage, the term is used to express the concept of a deep, penetrating examination of a person's innermost being. It is paired with "hearts" `{{G2588}}` to signify a complete and thorough knowledge of an individual's thoughts and feelings, demonstrating divine omniscience. The outcome of this searching is judgment, as Christ continues, "I will give unto every one of you according to your works" [[Revelation 2:23]].
### Related Words & Concepts
Several related words help clarify the context of `{{G3510}}`:
* `{{G2045}}` **ereunáō** (to seek, i.e. (figuratively) to investigate): This is the action performed upon the reins and hearts. The Spirit also **searcheth** all things, even the deep things of God [[1 Corinthians 2:10]].
* `{{G2588}}` **kardía** (the heart, i.e. (figuratively) the thoughts or feelings): This word is used in parallel with **reins** to denote the entirety of the inner person. God's covenant involves placing laws in their minds and writing them in their **hearts** [[Hebrews 8:10]].
* `{{G1097}}` **ginṓskō** (to "know" (absolutely)): The purpose of searching the reins and hearts is so that all the churches "shall **know**" who Christ is [[Revelation 2:23]]. This type of knowledge is also tied to eternal life [[John 17:3]].
* `{{G2041}}` **érgon** (an act, deed, doing, labour, work): The divine searching of the inner self is directly linked to judging a person's **works**. God is able to make grace abound so that believers may abound to every good **work** [[2 Corinthians 9:8]].
### Theological Significance
The theological significance of `{{G3510}}` is concentrated in its single, powerful use.
* **Divine Omniscience:** The word underscores that no part of the human mind is hidden from God. He "searcheth the **reins** and hearts," indicating a complete understanding of our deepest motives and thoughts [[Revelation 2:23]].
* **Inner Accountability:** It establishes a direct link between the inner life and divine judgment. The examination of the "inmost mind" is the basis for giving to each person "according to your works" [[Revelation 2:23]].
* **Total Scrutiny:** Used alongside **kardía** (heart), **nephrós** illustrates a comprehensive spiritual assessment. It is not merely outward actions that are seen, but the entire internal world of thought and feeling.
### Summary
In summary, while `{{G3510}}` is exceptionally rare, its use in [[Revelation 2:23]] provides a profound theological statement. As **reins**, it represents the deepest and most concealed aspects of the human mind. Its singular mention confirms that every hidden part of a person is fully known and searched by Christ, establishing a clear and sober connection between our innermost character and our ultimate accountability before God.
TRV