Ecotrain QOTW; Do we need a guru or teacher to grow spiritually

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Greetings wonderful and great people of this community @ecotrain . I'm so happy writing on this topic.
Two months ago, I and a friend argued on this topic.

Who is a guru?

A Sanskrit term for a "mentor, guide, expert, or master" of certain knowledge or field.
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Who is a teacher?

A teacher is a person who helps students to acquire knowledge, competence or virtue.
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• A guru works more than a teacher.
  We all need a guru and teacher to teach us spiritually but we don't depend or rely on them to grow spiritually. They can't teach us effectively to grow spiritually.

• The best teacher who make us grow spiritually is the Holy Spirit.
  There is no man that has secured the intelligence than the Holy Spirit.

But the Helper, the Holy Spirit, whom the Father will send in my name, will teach you all things and remind you of everything that I have told you - John 14:26

You need the Holy Spirit to dwell within you, and he will teach you ways to grow spiritually.

First of all, to grow spiritually, we need to be willing to grow spiritually.
One who is not willing, despite what a teacher or guru teaches him,he won't grow.
One who is willing, when he gets what's being taught, it aligns him.
Having a closer relationship with God, Reading and meditating on the word of God can also make you grow spiritually.

Thanks for reading.