The district court granted a refund after finding the taxpayers entitled to a charitable deduction under Internal Revenue Code of 1954 § 170(c)(1) for the market value of 9.2 acres of redwoods deeded to the City of Mill Valley, California. The government appeals.

In 1963, taxpayers bought for investment purposes 22 acres of land zoned for one-acre residential lots. Mill Valley had an ordinance allowing “cluster zoning” that would permit a subdivider to divide a tract into half-acre lots, notwithstanding the one-acre-lot-size rule, provided that equivalent land was preserved as open space.

The topography, location of the wooded areas, and aesthetic conditions in the 22 acres commended to the taxpayers a plan of development which would preserve the redwoods intact. Between 1965 and 1967, the taxpayers applied three times to the city for approval of subdivision plans. Each plan created a redwood park, with the balance of the land in streets and half-acre lots. The first two plans were withdrawn by the taxpayers. One of these had not been passed upon by the city. The city approved the second plan, but the taxpayers withdrew it for financial reasons. The third plan showed more half-acre lots than the second, and reduced the park acreage. The third plan was approved by the city on the condition that the 9.2 acres of redwoods shown on the plan be deeded to the city. The city adopted a resolution to that effect.

Upon the adoption of the resolution, taxpayers executed and delivered the required deeds to the city. On their 1967, 1968, and 1969 federal income tax returns, taxpayers reported the land transfer as a charitable contribution and took a deduction. The Commissioner disallowed each deduction, and this litigation followed.

This circuit has held that the term “contribution”, for the purposes of the § 170 charitable contribution deduction, has the same meaning as the term “gift” in § 102(a), as defined by the Supreme Court in Commissioner v. Duberstein, 363 U.S. 278 , 80 S.Ct. 1190 , 4 L.Ed.2d 1218 (1960). DeJong v. Commissioner, 309 F.2d 373 (9th Cir. 1962).

The Court in Duberstein stated that what controls is the intention with which the payment, however voluntary, has been made. 363 U.S. at 286 , 80 S.Ct. 1190 . A gift, according to Duberstein, must proceed from a detached and disinterested generosity. 363 U.S. at 285 , 80 S.Ct. 1190 . The broad sweep of the Duberstein language was properly questioned in United States v. Transamerica Corp., 392 F.2d 522 (9th Cir. 1968). Transamerica’s subsidiary had conveyed to the city private land which had been used as a public thoroughfare, on the agreement that the city would stop “badg *788 ering” the donor and would improve and maintain it as a public street. We affirmed the district court’s rejection of the deduction because the donor received economic benefit from the transfer: a quid pro quo.

Two years after Transamerica, this circuit decided Stubbs v. United States, 428 F.2d 885 (9th Cir. 1970), cert. denied, 400 U.S. 1009 , 91 S.Ct. 567 , 27 L.Ed.2d 621 (1971). We said that it is the dominant purpose of a transaction that is the determining factor; the expectation of a benefit need not be the sole purpose of a transaction in order to preclude treatment as a charitable deduction. We affirmed a trial court in its instructions that the existence of a quid pro quo could be considered by the jury as evidence that the dominant purpose behind the taxpayer’s transfer was the expectation of economic benefit. Stubbs teaches that motive and purpose are questions of fact.

The court below held for taxpayers by finding:

We approach the quoted finding with the deference dictated by the “clearly erroneous” standard of review. Fed.R. Civ.P. 52(a). Collman v. Commissioner, 511 F.2d 1263, 1267 (9th Cir. 1975). A finding is clearly erroneous, even though there is evidence to support it, if the appeals court is left with the firm conviction that a mistake has been committed. United States v. United States Gypsum Co., 333 U.S. 364, 395 , 68 S.Ct. 525 , 92 L.Ed. 746 (1948).

We cannot assert with conviction that a mistake has been made. True, as the government argues, there is an element of quid pro quo in the city’s approval of a desired cluster-zoning plan upon the dedication of the nine acres of redwoods. But the trial court found that the dominant motive of the landowners was to preserve the redwoods, and that the best way to do so was to give the land to the city. Circumstantial evidence tended to persuade the trier both ways. We are not at liberty to substitute our view of the subjective meaning of this evidence for that of the trier unless we can say that the trier’s view was clearly erroneous. We cannot.

In Coliman, supra, as here, there were elements of self-interest in the conveyance of land to the county for the widening of a street, but we held that the donative intent was dominant. In the case at bar, the trier found that the donative intent was dominant, and the record permits that finding.

The government’s brief tenders a second issue which we do not reach. The trial court entered a “finding” that the taxpayer’s basis in the property from which the gift to the city was carved was $85,000. The government now fears that this finding, which was not necessary to the judgment, will set up some sort of collateral estoppel that will have tax consequences with reference to future sales of lots.

The finding was neither mentioned in the judgment below, nor necessarily included within it, and we have no reason to believe that the trial court ever treated the issue as a part of the case. The question of the basis of the taxpayers’ property deserves full and complete consideration and a decision by the trial court before we express an opinion on the question.

The judgment of the district court is vacated, and the cause is remanded for further proceedings, consistent with the views expressed herein, on the issue of the taxpayers’ adjusted basis.

Vacated and remanded.