One of the points Roman Catholics bring out in support for the Filioque doctrine was that St Gregory of Nyssa apparently supported it:
"...that while we confess the invariable character of the nature, we do not deny the difference in respect of cause, and that which is caused, by which alone we apprehend that one Person is distinguished from another — by our belief, that is, that one is the Cause, and another is of the Cause; and again in that which is of the Cause we recognize another distinction. For one is directly from the first Cause, and another by that which is directly from the first Cause; so that the attribute of being Only-begotten abides without doubt in the Son, and the interposition of the Son, while it guards His attribute of being Only-begotten, does not shut out the Spirit from His relation by way of nature to the Father."
And apparently this letter from St Gregory of Nyssa didn't espouse the the view that the Son merely temporarily sends the Holy Spirit:
Thus, since on the one hand the idea of cause differentiates the Persons of the Holy Trinity, declaring that one exists without a Cause, and another is of the Cause; and since on the one hand the Divine nature is apprehended by every conception as unchangeable and undivided, for these reasons we properly declare the Godhead to be one, and God to be one, and employ in the singular all other names which express Divine attributes.
http://newadvent.org/fathers/2905.htm
"...that while we confess the invariable character of the nature, we do not deny the difference in respect of cause, and that which is caused, by which alone we apprehend that one Person is distinguished from another — by our belief, that is, that one is the Cause, and another is of the Cause; and again in that which is of the Cause we recognize another distinction. For one is directly from the first Cause, and another by that which is directly from the first Cause; so that the attribute of being Only-begotten abides without doubt in the Son, and the interposition of the Son, while it guards His attribute of being Only-begotten, does not shut out the Spirit from His relation by way of nature to the Father."
And apparently this letter from St Gregory of Nyssa didn't espouse the the view that the Son merely temporarily sends the Holy Spirit:
Thus, since on the one hand the idea of cause differentiates the Persons of the Holy Trinity, declaring that one exists without a Cause, and another is of the Cause; and since on the one hand the Divine nature is apprehended by every conception as unchangeable and undivided, for these reasons we properly declare the Godhead to be one, and God to be one, and employ in the singular all other names which express Divine attributes.
http://newadvent.org/fathers/2905.htm