The phrase "a simple but essential" is correct and usable in written English.
It can be used to describe something that is straightforward yet crucial or necessary in a particular context.
Example: "This guide provides a simple but essential overview of the project's requirements."
Alternatives: "a basic yet vital" or "a straightforward yet important".
On the other hand, by a simple but essential lemma (Lemma 2.16), we can prove many fixed point results in this new structure.
The present parametric study using a simple but essential model explicitly demonstrates that creep dislocations are, in theory, not always required for the raft formation.
Urine analysis is a simple but essential test for patients with renal disease irrespective of its cause, but urine dipstick detects only albumin and is unreliable for detecting myeloma paraprotein.
With features like this we see that a phone can also work in a very simple but essential way.
These tools vary from those that help you manage projects and arrange events, to others that enable you to share large files, or schedule a meeting – in other words, relatively simple but essential things.
But Ms. Lofgren deserves some credit, Washington ethics lawyers said, for taking seemingly simple but essential steps like filling a dozen staff vacancies, including appointing a new staff director, R. Blake Chisam.
"Seeds are what gives us life, and we have to reclaim this simple but essential wonder, that food is not just a commodity, but a life-giving blessing".
A lazy ladies' man? — to merely make the point, simple but essential, that not only is it far too soon to say, but that in any case, the whole idea of a special class of "elite" quarterbacks into which one might or might not be ushered is ridiculous.
One simple but essential benefit is the ability to query a database for an annotation (an assertion about a gene product) based on a particular type of evidence.
And Houellebecq, in court, made the simple but essential point that to attack people's ideologies or belief-systems is not to attack the people themselves.
