Question: I have trouble with this sentence. "Reason" is singular and I want to use the present tense, not the past. 

Which one is the correct one? 

> 
> * The reason **lays** in the facts
> * The reason **lies** in the facts
> 
> 
> 

Thanks a lot

Context: this sentence is used as an argument encouraging the other persons to look at the facts as they will provide the reason.

Answer: 
When we look at both sentences, we find that there is no object. So it is clear that we need to use an intransitive verb. As the verb "lay" is a transitive verb (needing an object), which means to put somebody or something down in a particular position, its use in the sentence meant is out of the question because it is neither an intransitive verb nor it has the sense needed for the right sentence.

On the other hand, the verb "lie" is an intransitive verb, which has no object. In addition to its main sense i.e. to put yourself in a flat or horizontal position so that you are not standing or sitting, it also means to exist or to be found that is the right sense needed in the sentence. So it's wrong to say that the reason lays in the facts. Instead, it's right to say that the reason lies in the facts.
You asked for the *present tense,* and it's easy! 

The correct one is...

> 
> The reason *lies* in the facts.
> 
> 
> 

Quick tip is -**broadly,** the word *lay* requires a direct object and *lie* does not. That said, you can *lie down* on the floor but you *lay your laptop* on the table. 

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The things go haywire when it comes to the past tense. Because the past tense of *lie* is *lay!*.

Good read is here on [GrammarGirl](http://www.quickanddirtytips.com/education/grammar/lay-versus-lie?page=1).